ERP Systems in SMEs: An Extended Literature Review

This review summarizes research on enterprise resource planning (ERP) systems within the domain of small and medium-size enterprises (SMEs). Due to the close-to-saturation of ERP adoptions in large enterprises (LEs), ERP vendors now focus more on SMEs. Moreover, because of globalization, partnerships, value networks, and the huge information flow across and within SMEs nowadays, more and more SMEs are adopting ERP systems. Risks of adoption rely on the fact that SMEs have limited resources and specific characteristics that make their case different from LEs. The main purpose of this article is to shed the light on the areas that lack sufficient research within the ERP in SMEs domain, suggest future research avenues, as well as, present the current research findings that could aid practitioners, suppliers, and SMEs when embarking on ERP projects. Moreover, this research highlights the theories, frameworks, and research approaches and methods currently adopted in ERP for SMEs literature.


Introduction
ERP systems have received a substantial attention from both academia and practice. Many research articles dealing with ERP systems have been published, covering various topics and issues. Moreover, a number of ERP literature reviews have been conducted[e.g., 1, 2-4]. These reviews provide overviews of existing ERP literature fro m a general point of view. Since ERP literature is a broad topic, we focused our review on ERP in SM Es that would provide a more detailed analysis and deeper understanding of this domain.
SMEs have been recognized as fundamentally d ifferent environments compared to large enterprises [5]. In relat ion to ERP imp lementations, organizational size plays an important role [6,7]. The literature argues that little attention has been given to research on ERP in SM Es, as the majority of the ERP studies are based on findings from large enterprises [8,9]. Up to our knowledge, there are no existing literature rev iews covering this particular area.
The objective of this paper is to present a comprehensive review o f literature on ERP in SM Es in order to illustrate the status of research in this area, and to assist researchers in pinning down the current research gaps. A total of 77 art icles were reviewed and organized into ERP life-cycle phases as described by Esteves et al. [10].
The rest of the paper is organized as follows. Section 2 presents the research methodology. Section 3 prov ides an

Research Methodology
Literature reviews represent a well-established method for accumulat ing existing knowledge within a domain of interest. In this article we have applied a systematic rev iew approach [11]. This approach is characterized by adopting explicit procedures and conditions that minimize b ias [11].
The review covers articles published between the years 1999-2009. We have narrowed down the search process through a condition, that the articles need to be published in peer reviewed journals or conference proceedings. Moreover, no delimitation has been imposed on the outlets' field, to enable potential research results from various fields. The following search procedures have been applied to provide a comprehensive and systematic methodology.
An initial search was done through Google Scholar. The search option was limited to art icles' tit les. The keywords: ERP, Enterprise Recourse Planning, SM Es, Small and Medium Enterprises, and their co mbinations were used.
1. Due to their h igh relevance for IS research, another search in EBSCOhost and Web of Science was conducted. The search procedure was restricted to the same keywo rds as in the previous step. In addition to the title area, the abstract and keyword parts of the articles have been included into the search.
2. In order to ensure that no articles were o mitted by the search engines used in the previous steps, we went through tables of contents of selected outlets. These included top IS journals (MISQ, ISR, CA CM, JM IS, ISJ, and EJIS) and journals related to the research field (JEIM, EIS, and IJEIS). We searched for the keywords across all issues published during the delimitated period. The same procedure was applied to the proceedings of four top IS conferences (ICIS, ECIS, AMCIS, HICSS).
3. Both authors carefully read the articles' abstracts to check their relevance and adequacy for the review. On ly articles directly addressing ERP in SM Es were selected.
4. In addition, we conducted a secondary search through scanning all the selected articles' reference lists, in order to identify further potential literature sources.
In order to better organize the rev iew arrangement, we adopted the ERP life-cycle framewo rk developed by Esteves et al. [10]. It consists of six phases representing different stages an ERP system goes during its life-cycle within an organization. The phases are: adoption decision, acquisition, implementation, use and maintenance, evolution, and retirement. A brief description of each phase is provided in section 4. In addition, the authors independently classified the articles into a concept matrix [12], wh ich included the research themes, approaches, theories, and methodologies. Results were consequently compared and discussed in order to achieve consensus on the articles' classification. It is important to mention that an article could fall in one or mo re phases and themes.
A number of research articles proposed various ERP lifecycle models[e.g., 10,13,14,15]. There are t wo important reasons why we adopted Esteves et al. [10] framework. First, it applies more granular approach compared to other models. It provides more detailed understanding of the ERP life-cycle and thus better classification of the articles. In particular, the framework clearly distinguishes between system adoption and acquisition, as these are two diverse phases that are usually merged in other models. Furthermore, the framework separates between system evolution and retirement. Second, it has been previously applied by other researchers reviewing ERP literature [3,16]. This enables a comparability of our findings with formal literature reviews.

Overview of the Articles
In total, we reviewed 77 articles. Of these, 48 are journal articles and 29 conference p roceedings. The articles were published in 44 various outlets, involving 26 journals and 18 conferences. As illustrated in tables 1 and 2, journals had the biggest share of publications with JEIM leading by 10 articles, and AMCIS by 5 conference publicat ions.
The review shows a gradual increase in research interest in ERP in SM Es (fig 1.), with a maximu m of 20 publications in 2008 fo llo wed by a decline to 11 articles in 2009. Figure 2 illustrates the research methods distribution among the articles. Case studies and surveys are clearly the do minant methods, while other methods are comparably less frequently used.    As shown in Figure 3, the imp lementation is the most discussed phase in literature, which is in align ment with several formal literature reviews on ERP systems [3,16]. Moreover, the figure illustrates the clear difference of research focus among the phases. Table 4 provides a list of publications that have adopted theories or established frameworks. So me papers have adopted more than one theoretical lens. The richness of theory or framework use varies among articles; however, we list the articles that explicitly mentioned their adoption and use of theories.

Findings
In this section, a brief overview of the articles for each phase is presented. It is not intended to provide a detailed discussion of each article, but rather an attempt to briefly present the topics and issues discussed in literature. For the articles rev iewed in each phase, refer to Table 3 below.

Adopti on Decision
During this phase, organizations identify their business and technical needs, and question the need for an ERP system. Cu rrent ERP literature has tackled several issues related to ERP adoptions in an SME context and environment.
Adoption dri vers. Several papers discussed ERP adoption drivers in SM Es fro m different angles. Few studies [20,21] have adopted the Technology-Organizat ion -Environment framework (TOE) to develop a model that can be applied to predict which SM Es are mo re likely to become adopters of Enterprise Systems (ES). Although, the model developed was applied to predict the factors influencing the willingness of SMEs to adopt ES, nevertheless it does not differentiate between factors that affect each type of system solely (e.g. ERP, SCM ). In [20,21] they concluded that SMEs' ES adoptions are more influenced by internal organizational and technological factors, sooner than industry and market related factors. On the contrary, a study [23] suggests that, the higher an SME collaboration within a network of organizations, the more likely to adopt an ES, and more environ mental influence it will get. Adoption evaluation. A study conducted in Ind ia argues that business needs, competition, market survival, and customer retention are among the main drivers that force SMEs to adopt ERP system [29]. Ravarini et al. [30] propose a pre-adoption framework for evaluating the suitability of an ERP system in alignment with the degree of business complexity, and the extent of change that a company envisions to achieve. Blackwell et al. [27] developed a decision-support systematic methodology that assists decision makers in regard to adoption decisions and could enhance the overall outcomes fro m the ERP adoption project. Other studies states that CEO's characteristics and the ERP perceived benefits are correlated with ERP adoptions' outcomes in Taiwanese SMEs [25]. ERP cost per se is not a major factor in adoption decisions [25], especially in the adoption or non-adoption of free open source ERP systems in co mparison to proprietary ERPs [17].
Organizational characteristics. Other researchersstudied the influence of specific organizations' characteristics on ERP adoption decisions. Research results shows that business complexity is a weak predictor of ERP adoption [7], while organizat ion size is a strong adoption predictor [6,7,22,26]. Moreover, SM Es' willingness and readiness of adopting ERP systems are affected by industry type in manufacturing firms [22,31]. Other studies argue that the scarcity of financial resources, and the challenges that face SMEs wh ile evaluating and selecting ERP do not have an influence on ERP adoption decisions [24], and that adoption drivers may vary according to SME size [32].
Other adoption issues. Several adoption-related issues were discussed in literature. A study by Muscatello et al. [8] reported that project management activ ities have a huge influence on the success or failure of ERP adoption projects in US manufacturing SM Es. On the contrary, another research shows that formalized management does not promise imp lementation risk minimizat ion in small manufacturing co mpanies [33]. In [34,35] they developed and applied a mult i-d isciplinary Customer-Centered ERP Implementation (C-CEI) method. They present C-CEI as a tool that could assist SMEs in selecting appropriate ERP Systems, which match their process requirements. They argue that this method would decrease the risk of ERP and organizations misalign ment.
One of the few ERP market ing studies has been done by [28]. The research had a vendor-customer perspective. The paper construes that ERP suppliers' marketing abilit ies and customer reach strategies determine ERP diffusion and adoption success in SM Es, rather than SM Es' lo w demand or failure in the adoption process.

Acquisition
This phase includes the process of ERP package and vendor selection that best fit the organization requirements.
Factors affecting selection. In order to better understand and evaluate the acquisition and selection process, many studies identified the factors that affect ERP selection in SMEs, and proposed criteria to optimize the selection process. Results show that internal organizational factors like business complexity, change management, and external factors like supply chain partners, and the pressure of value networks affects the ERP selection process in Greek SM Es [36][37][38]. While other research conducted in Australian SM Es, suggest that cost drivers, functional requirements, flexibility, and scalability of the ERP system [41], and the degree of ERP align ment/fit with the business processes [40] have a great influence on acquisition decisions. Moreover, in [18,19], they compared Finnish small, mediu m, and large enterprises. They explored the relat ionship of enterprise size with the ERP selection process. Their results show that small companies appear to have problems with the amp le informat ion for decision-making, and sufficiency of participation fro m different organizational functions in the ERP system selection phase.
Selection criteria. This part presents research that developed or explored the criteria that SM Es use in order to select their ERP systems. In [44], they stated that the ERP fit with organization business processes appeared to be the most important selection criterion in Nordic European SM Es, whilst others developed criteria that can aid SM Es in the selection process. The dimensions were local support, affordability, suppliers' business domain knowledge [29], or a methodology for selecting the best-fit ERP system with ma ke-to-order (MTO) SM Es' environ ments [39].
In-house developed systems. In ERP for SM Es literature, few research papers questioned the feasibility of in-house developed systems over off-the-shelf ERPs as in [45,46]. These papers argue that standard ERP packages could compel rigid structures and inflexibility on niche SM Es, and in-house developed systems might be more suitable in so me cases. Correspondingly, Sledgianowski et al. [47] conducted a case study and reported that in some cases, ERP offshore outsourcing could be more feasible and beneficial for SM Es.
Other acquisition issues. CEOs' technology awareness, emp loyees' IT competence, firm size, ERP co mpatib ility [49,51], and project management [8], are among the CSF for selecting the right ERP for SM Es. Other researchers furnished recommendations and methods that could be of assistance in managing and min imizing the key risk factors during the ERP selection process [33,48]. Other studies went further and conducted a comparative analysis of the impact of size on the selection procedures in LEs and SMEs [42,52], as well as, across industrial sectors in Taiwan [50].

Implementation
This phase includes the actual ERP installation, customization, business process re-engineering (BPR), and all other activit ies that align the system with the organization requirements. The ERP implementation phase is very critical, as well as, the most resource consuming phase. Several studies focused on different corners during the implementation process.
Critical success factors. The adequacy of general-ERP implementations CSF in relat ion to Belg ian SM Es-specific characteristics were examined in [53]. The study discovered that most of ERP CSF apply to SM Es with some exceptions. Likewise, a study analyzed imp lementation success factors in small size firms and concluded that the CSF in literature are adequate when applied on small organizations [49]. Another article presented an analysis of the CSF related to Chinese SM Es' characteristics [57]. While top management support, ERP system quality, and knowledge sharing during implementations, were found key CSF in Thai SM Es [54], however, BPR was found to be a key factor of success [57].
In [56], the authors developed a framework for ERP implementation CSF assessment in s mall manufacturing firms. Moreover, Loh et al. [9] used the Process Theory in order to identify the implementation crit ical elements through case studies in the UK. The study concluded that critical success factors, crit ical people and critical uncertainties contribute to the success or failure o f ERP implementations in SM Es. Reuther et al. [41] and Marsh [40] carried out an analysis to determine the key success and failure factors of ERP implementations in Australian SM Es. Further, in Snider et al. [55], they presented a detailed case analysis of successful and unsuccessful imp lementations in five Canadian SM Es. Finally, a new CSF ranking that would be more adequate to SMEs environments is needed [57]. SME characteristics.
As organization-specific characteristics and contexts have been always important research aspects, they attracted researchers to investigate their imp lications on the ERP implementation process. A study presented a conceptual model that could help implementers, vendors, and consultants imp lementing SAP R/3 ERP to better understand the system expectations by SMEs in certain contexts or regions (e.g. Australia) [59]. Since organizat ion size and business comp lexity affect ERP implementations, it was reported that implementations in Irish SMEs are usually easier and shorter in duration than those reported in ERP literature [58]. In [60], through adopting a vendor's perspective, they recommend that ERP systems need to be localized according to the local management features. SM Es' characteristics and culture play an important role in the success or failure of ERP implementations in Belgian SM Es [53], while cu ltural issues did not play a major ro le in ERP implementations within Chinese SM Es [57]. Moreover, ERP implementation methodologies differ between different organization sizes and business complexit ies, as LEs are more reluctant to adopt a Big-Bang approach than SMEs [6]. Further, a comparative analysis on ERP imp lementation rates and success, between different organization sizes and industrial sectors in Taiwan shows that ERP implementations in electronic and science industry SMEs are usually mo re successful than those in traditional industry [50] Impact of consultants. Although experienced consultants can play an important role in correct ing their client co mp anies' "u nr ealistic exp e ctations" o f E RP implementation s [58]; however, a study in Taiwan shows that consultants could still face resistance from SM Es' managers [58]. On the contrary, through Grounded Theory approach, [62] states that if SM Es imp le ment an SM E-specific ERP system, they will not need external consultancy, which will decrease their investments dramatically. Moreover, SM Es will save time and high costs of training, which are usually, associated with standard ERP packages.
Risk management. Few papers discussed risk management during ERP implementations in SMEs. In [63], they portrayed how SMEs should deem and manage the risks in their ERP implementation projects. Poba-Nzaou et al. [33] discuss methods for ERP imp lementation risk management and minimization in manufacturing SM Es. Iskanius [48] applied and advocated for using the risk analysis method (RAM), to identify and asses the critical risks of the ERP implementations, and to apply the characteristics analysis method (CAM) in o rder to help SM Es in div iding ERP implementation projects into sub-projects.
Other i mplementati on issues. Project activities, coordination, and project sponsors [8], employee behaviour, individual characteristics of ERP pro ject management's team, and organizat ion culture have a great effect on the success of ERP imp lementations in SM Es [64].
Chan [67] emphasized the importance of knowledge capturing and management during implementations in SMEs. The study identified the essential knowledge required for ERP imp lementations, and proposed a framework to manage it, through matching the required knowledge with the ERP capabilit ies and features. Moreover, Zain [69] proposed the application of the FA ST (Framework for Application of Systems Thinking) system develop ment methodology while implementing ERP systems in cigarette manufacturing SMEs. The study concludes that using such an agile method could assist in reducing and filtering co mmon problems that occur during ERP implementations.
Newman et al. [66] conducted a study on two Chinese small and med iu m co mpanies. Th rough business process modeling, the study compares and analyzes the process of ERP imp lementation in these two companies, and discusses their decisions concerning business process re-engineering. Likewise, in [68], they emphasized the importance of business process modeling, management and re-engineering ex ante imp lementations. Their study was a simulat ion on niche Italian SM Es. They conclude that in some cases, ERP systems should be customized to fit with n iche SM Es and not vice versa, as they might lose their competitive advantage by comply ing with standard ERP processes.
In comparison with LEs, SM Es suffer scarcity of financial resources; however, only two papers have discussed ERP costs in an SME context. Through a survey analysis, Equey et al. [65] investigated and evaluated the costs that occurred during ERP imp lementations in several Swiss SMEs. They found that size, consultants' experience, and people characteristics have a great influence on ERP projects costs. Moreover, implementations at larger companies generally cost much more than at smaller co mpanies, however, a survey by Mabert et al. [6] shows that cost of ERP software at SMEs is higher as a percentage of overall cost than at LEs.

Use and Mai ntenance
After the sizeable efforts and investments in ERP implementations, companies start to use the systems. Many issues emerge after the systems' "go-live", like system acceptance, user satisfaction, benefits realizat ion, system utilizat ion, and maintenance.
Benefits. ERP benefits expectations and realization have always been problematic issues for the majority of companies. The difficu lty originates to several reasons. Here we present some of the issues discussed in literature.
Although benefits realized could differ in each SM E industry [41], or organization size [6], several studies argue that realizing benefits from ERP systems can not be done unless there has been an ex-ante efforts to define and audit these expected benefits [41,[70][71][72]75]. However, if SM Es make the right choices in the ERP selection phase, some benefits fro m ERP systems could be self-evident [41,73,74] and tangible [40]. Moreover, a study in Swiss SMEs concludes that the benefits realized fro m ERP systems exceed their costs [76]. Whilst another study reports that benefits realized fro m ERP systems are h igher in LEs than SMEs [77].
Use. Even if the ERP imp lementation was successful, for many practit ioners and researchers, the usage of the systems is considered the moment of truth of an ERP system. If the implementation was successful but the system was not used or "accepted" by users, then it is considered a failure. Thus, many studies were focused on use, user motivation and satisfaction related issues.
Adopting ERP's standard best practices is the aim of many SMEs, as they see it as a gateway for standardization and regional or international markets. However, through a dialectic perspective, Nathanael et al. [81] argue that best practices, when imposed on SMEs, might affect the motivation of the users, and lead to the loss of the know-how and the competitive edge of these companies. Moreover, if ERP systems were mo re agile and responsive, this would utilize the system use and offer a co mpetitive edge for MTO and traditional manufacturing SM Es [78][79][80]. A case study results show that user satisfaction and system acceptance rates in LEs are h igher than those of SMEs [77]. Further, Wu et al. [50] argue that user satisfaction in Taiwanese electronic and science industries' SMEs is higher than of LEs in the same industry and SMEs in other industrial sectors. In order to minimize the risk of challenges related to user acceptance and motivation, Huin [85] developed a mult i-agent model that can decrease the risks related to system use and user acceptance, through organizing the ERP project management activities. In addition, enhancing user communication, training, and obtaining short-term successes could positively impact the mot ivation and users' system acceptance rates within SM Es [48]. In [63], they state that risk management is a continuous process. They also reco mmend that benefits and risks in the use and maintenance phase should be re-assessed once or twice a year, in order to manage the impact of stirring risks, and to govern system usage and avoid slipping into old procedures ERP impact. Introductions of new informat ion systems in companies are accompanied by changes with their business processes, structure, and co mmunications within those companies. Likewise, ERP systems affect many corners within organizations. A case study in an MTO med iu m-sized company reports that, the ERP adoption had a positive impact on v isibility, quality, and control of informat ion, which in turn enhanced the decision making process [84]. Using the Six Imperatives framework, Argyropoulou et al. [36,37] evaluated the impact of ERP systems on Greek SMEs' business performance. In [82], they attest that ERPs impact on productivity is moderated by SM Es size. Another study [83] adopted an organizational cross-functional point of view in order to evaluate the impact of ERP implementation on different business functions. The study concludes the smaller the size of the organization, the more it will benefit fro m the ERP system's cross-functionality capabilit ies.

Evol uti on
This phase involves the extension of ERP systems through integrating other systems or applicat ions, such as customer relationship managements, supply chain management, and advanced planning and scheduling systems.
In [86], the authors state that SMEs which had successful ERP system imp lementations, are now investigating means of how to extend it in order to support their external operations. The study concludes that, with the use of Internet, ERPs can be extended to cover SMEs' entire supply chain, which in turn will enhance their external operations and relationships. Another study developed an ontology-based conceptual framework. The study argues that, representing the implementation processes using ontology domains, classes, and relat ions could enhance the coordination and project management during ERP imp lementations in SMEs [88]. Further, Metaxiotis [87] carried out a study to investigate the raison d'être for integrating knowledge management (KM) systems and ERP systems in SM Es. The study suggested an ERP extension and KM integration framework.

Retirement
Retirement phase corresponds to the stage when an ERP system is substituted by another information system. No articles were identified in this phase.

Discussion and Future Research Avenues
The reviewed art icles are spread across 44 various outlets. Among the outlets, we have recognized only one special journal issue in JEIM focusing on adoption of ICT by SM Es, which included several ERP related research papers. As the research interest on ERP in SM Es is increasing, research outlets should pay more attention to this domain.
In general, 77 art icles across 10 years period is relatively a low nu mber of publications. Despite the need for research on ERP in SM Es was recognized in prev ious literature, still the amount of research conducted on this issue is limited. Thus, more research needs to be carried out in order to gather sufficient knowledge about this phenomenon, as SMEs did not receive appropriate attention in co mparison with ERP in LEs.
Based on our ERP in SM Es literature review, in the following part we present some research gaps and suggestions organized according to life-cycle phases: Adoption. In IS literature in general, and in ERP literature in specific, the term "adoption" is variably perceived by authors. So me authors perceive it as a final stage in which users accept the ERP system, and others define it as the preliminary stage when companies decide on investing in an ERP system.
Although some papers tackled the pressures or motivations imposed by suppliers and partners for ERP adoptions by SMEs, still there is a gap in studying national government policies, rules and laws and their consequences on ERP adoptions in SM Es.
Acquisition. The current literature lacks focus on new technologies (e.g. Software as a Service-SaaS) and their implications on ERP projects. Moreover, ex-ante cost estimation, financial feasibility, and investment evaluation studies of ERP projects have not been identified in our review of literature. Furthermore, literature lacks cases that compare between SM Es'-specific ERP and general ERP systems, as well as, industry-specific ERP packages vs. general ERP ones.
Implementati on. So me articles examined ERP p rojects' success and CSF in SM Es, however, there was no clear definit ion for success. Moreover, the differences of ERP implementation methodologies and their impact on ERP projects had scant attention.
Use and maintenance. Interface language and ERP localization and their effect on user satisfaction are rarely discussed in literature. In addit ion, post implementation audit strategies and ex-post investment and financial evaluations were not discussed in literature.
Evolution and retirement. Regarding the ERP life-cycle phases, the first four phases were noticeably captured in literature. As recently SMEs started to adopt ERP systems to enhance their operations, value networks, and expansion goals. Thus, it is not surprising to find very few papers discussing ERP evolution, as ERP systems require time to mature enough and recompense in order to convince organizations to extend them further.
We were not able to find any article that directly addresses the retirement phase. Thus, we recommend more focus on the evolution and retirement phases, as they can shed the light on the motivations for extending or rep lacing ERP systems. General co mments. Although comparisons between SMEs and LEs cases were found in literature, yet the size differences among SM Es were seldo m d iscussed, and they could provide valuable research insights. In relation to type of organizat ions, the cases studied were often conducted in traditional manufacturing SM Es. On ly few art icles elaborated on the manufacturing context or type of industry, 41 19 17 Research Approach QUAL QUANT MIX however, difference in production strategies or industries could produce different research findings. Besides the SME type and context, another important observation evolved fro m our review, which is the "SMEs" perception. Some studies delimitate SM Es d ifferently. So me research define an SME in a qualitative manner (e.g. [28]), while the majority of them define SM E in terms of number o f employees, annual revenue, or their co mb ination. However these numbers differ as well, particu larly depending on the geographical location of the study. Adopting the European Union's definition, most studies define SM Es as organizat ions with less than 250 emp loyees. Interestingly, some researchers have applied a more granular approach distinguishing between subgroups (e.g. s mall, micro) within SM Es (e.g. [16,18,19]). Both, type of investigated organizations and SME defin itions are likely to influence the research findings. Therefore, researchers need to be cautious about these issues and elaborate on specificity of each particu lar environ ment.
While there were many studies with a national perspective, however, we were not able to find any cross-national studies. This kind of co mparison might be fruitfu l for ERP literature in SM Es. Also, most of the studies were embarked in America, Australia, Eu rope or Asia. It would be p rolific to have some studies on African or Middle Eastern SMEs as well.
Surveys and questionnaires can be quantative or qualitative in nature. Although surveys were highly used, however, figure 4. shows that 53% of the research publications have adopted a qualitative research approach. As many publications have reported that they conducted surveys, still they reported and analyzed them qualitatively, and only 25% of the publications have used a quantitative approach. According to Eisenhardt [89], mu ltiple data collection methods could strengthens theory grounding and theory building through evidence triangulation. Thus, 22% of the studies have adopted mixed research approaches, through combin ing both qualitative and quantitative approaches and data collection methods. Most often a combination of case studies and surveys was employed. Qualitative studies can provide rich exp lanations and explorations to emerg ing phenomena; however, we call for a focus and use of other research approaches, as they can provide different angles of data interpretation. Moreover, use of theories in ERP literature in SM Es is very limited, as only 15% of the papers have adopted a theoretical lens (see fig. 5). This could be attributed to many reasons, among wh ich, the complexity of finding relevant theories that could explain certain technical issues for example. St ill, we call for mo re theory use, theorizing, and reporting on the difficu lty of adopting theoretical lenses if any.
As shown in figure 2, only two Action Research (AR) papers were identified, however, we think that AR and similar engaged methods could provide very valuable hands-on experiences for ERP in SM Es literature and practice.
There is also a need for more papers on Open Source (OS) ERP systems, and co mparative studies of OS ERP vs.
proprietary ERP systems. While SM Es usually have limited resources, and costs and benefits from ERP imp lementations continues to be an issue, more research need to address these topics.
Finally, existing literature have usually adopted a one sided perspective in data collection (e.g. customer side), while other perspectives could enhance the understanding of certain phenomena. Finally, it could be beneficial if research provides some reports on ERP failure cases, which might assist stakeholders in avoiding previous pitfalls.

Conclusions
This paper contributes to both research and practice through providing a comprehensive literature review of ERP in SM Es. For pract ice, the paper sheds the light on past and recent issues, challenges, and success stories that can guide consultants, vendors, and clients in their future projects. For research, the organization of literature in ERP-lifecycle phases can aid them in identify ing the topics, findings, research methods, theories, and gaps discussed in each phase of interest. Finally, we have provided our observations and future research suggestions that would enrich our knowledge in this domain.