You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: The Impact of Digital Financial Services on Firm's Performance: a Literature Review 
Chapter Title:  Research gaps 
1. Abstract of Cited Paper (BIB001):  Internet web sites have become an important alternative distribution channel for most banking institutions. However, we still know little about the impact of this delivery channel on bank performance. We observe 424 community banks among the first wave of US banks to adopt transactional banking web sites in the late-1990s, and compare the change in their 1999-2001 financial performance to that of 5175 branching-only community banks. Whereas today virtually all viable community banking franchises offer he Internet banking channel, studying this earlier time period allows us to make clean comparisons between subsamples of "brick-and-mortar" and "click-and-mortar" community banks. We find that Internet adoption improved community bank profitability, chiefly through increased revenues from deposit service charges. Internet adoption was also associated with movements of deposits from checking accounts to money market deposit accounts, increased use of brokered deposits, and higher average wage rates for bank employees. We find little evidence of changes in loan portfolio mix. Our findings suggest that these initial click-and-mortar banks (and their customers) used the Internet channel as a complement to, rather than a substitute for, physical branches. 
2. Abstract of Cited Paper (BIB002):  To date, Internet banks worldwide have underperformed newly chartered traditional banks mainly because their higher overhead costs. This paper analyses whether this is a temporary phenomenon and whether Internet banks may generate scale economies in excess of those available to traditional banks and/or they (and their customers) may accumulate experience with this new business model, which may allow them to perform as well or even better than their peers, the traditional banks. To this end, we have followed the same analytical framework and methodology used by DeYoung (2001, 2002, forthcoming) for Internet banks in the United States although the limitations in the availability of data as well as the existence of different regulatory frameworks and market conditions, particularly in the retail segment, in the fifteen European Union countries have required some modifications to such methodology. The empirical analysis confirms that Internet banks show technologically based scale economies, while no conclusive evidence exists of technology based learning economies. As Internet banks get larger, the profitability gap with traditional banks shrinks. To the extent that Internet banks are struggling to prove themselves a viable business model, European authorities may encourage a larger number of consumers to use this delivery channel, by tackling consumers? security concerns. This would allow Internet banks to capture more of the potential scale efficiencies implied in our estimations. 
3. Abstract of Cited Paper (BIB003):  Purpose – Online banking has attracted a great deal of attention from various bank stakeholders such as bankers, financial service participants, and regulators. The purpose of this paper is to analyze the online banking service performance of giant US and UK banks. Risk analysis is also conducted.Design/methodology/approach – This paper connects the principal component analysis (PCA) method with the data envelopment analysis (DEA) method to estimate the online banking performance. Data are collected from 2007 annual reports of giant banks in the USA and the UK including both financial and non‐financial variables.Findings – Most giant banks are performing well based on DEA analysis. Employees turn out to be a key variable that contribute most to banks' revenue. Different DEA models can be classified into cost‐ and online‐oriented models, which is consistent with existing work based on data from other nations.Originality/value – This paper presents a unique demonstration of using PCA and DEA for evaluation ... 
4. Abstract of Cited Paper (BIB004):  AbstractE-banking has become one of the most popular methods of banking that has experienced a considerable expansion during the last few years. However, there is relative dearth of empirical studies examining the impact of e-banking on performance of banks. Though e-banking is gaining acceptance in Bangladesh, impact of e-banking on bank’s performance is yet to be established. This paper fills this gap. Using panel data of 13 banks over the period of 2003–2013, this study empirically investigated the impact of e-banking on the performance of Bangladeshi banks measured in terms of Return on Equity, Return on Assets and Net Interest Margin. Results from pooled ordinary least square analysis show that e-banking begins to contribute positively to banks’ Return on Equity with a time lag of two years while a negative impact was found in first year of adoption. Empirical findings of this study is of greater significance for the developing countries like Bangladesh because it will invoke the attention of the ban...

Literature Review:
A review of prior, relevant literature is only effective if it creates a firm foundation for advancing knowledge, closes the outdated research areas, identifying the possible research gaps while uncovering areas where future research is needed BIB001 . Given the findings in this literature review, we also outlined certain areas of research where future research should be aiming at. Most of the studies included in this literature review are of quantitative in nature. However, it has been observed that data pertaining to the digital channels used as DFS is either very limited or not empirical in nature. Although financial data indicating the performance of the company is available easily, however, secondary data for digital payment channels were non-existent in the early stage (the 2000s) of emerging DFS. But nowadays availability of resources increased significantly. Hence to improve the quality and applicability of their studies, researchers are expected to use better quality data to validate their research. IT is no more a source of enjoyment for developed countries only. The developing and under developing countries in the recent years (last one decade) invested a lot to develop the IT infrastructure. Both the traditional and digital banking services improved and increased. Since last one-century crossing borders have proved to be difficult both in developed and developing countries. Hence the DFSs varied from country to country with exception of few products e.g globally accepted credit cards. Few of the main reasons for variation are regulations, social and cultural environment and market structure. Therefore, it is difficult to generalize the results of many DFS research. In our literature review we could only find four BIB002 , , BIB003 , BIB004 ) multi-country studies. Future research covering different countries with comparative market structure could improve the generalizations. A comparative analysis of DFSs performance and its effect on firm with respect to customer based in rural and urban areas could be interesting as well. The impact of DFSs is no more limited to the banking industry. It is widely being used by other industries as the payment solution for various purposes e.g online shopping, grocery stores, supermarkets, insurance, mobile service providers and trading etc. The 39 research articles included in this review studied the impact of DFS on banking industry (as a service provider) only. We encourage to include more industries e.g IT, Telecom, Energy, Healthcare, Automotive, and Supply Chain companies (as service providers or co-providers) to see how are they getting benefit from such customer oriented services. This more representative sample would provide valuable insights into performance and extend understanding. So far, the research is focused on digital currencies being used for digital channels in DFS. However, cryptocurrencies (e.g bitcoin, ether, monero, Zcash and dash etc) can also use the same digital channels in DFS. Future research on how cryptocurrencies will affect the performance of offering and accepting firm could be interesting. The comparison of crypto versus digital currency for the same accepting firm could also provide interesting results to understand the performance. The branchless banking e.g M-Pesa, Easypaisa, G-Cash, Ready-cash etc (in developing) and Paypal, skrill, Paysafecard and Neteller etc (in developed countries), are serving the masses and now a major competitor for traditional banking model. In developing countries, such services are being provided by mobile service providers while in developed by nonbank companies. The future research to investigate the role of such services in the profitability and performance of mobile service providers' companies could be interesting and the comparison of branchless banking in developed and developing countries can extend understanding for adoption, efficiency, performance and trust. Although most of the studies (82%) support the argument that DFS improve the performance and profitability of the firm, however, few studies (18%) doesn't support this argument. Also few studies e.g BIB005 ,  ,  ,and indicated the time lag of more than two years to get the benefit from such IT investments. This leads to an important aspect missing in the literature that how much should be digitized or what should be the optimal digitization in terms of return (both financial and non-financial) on these investments. Also which factors are affecting this optimal digitization. For example, it could be interesting to investigate whether Technological advancement and customer affinity (awareness to use) are running at the same pace or not. Because if the technology is running at the higher rate than the consumer awareness and utilization, then the adoption by the organizations would likely lead to loss or the lag period to get benefit may increase more. The other important area missing in the literature is the state bonds and lotteries. Previously one could only buy such products at particular bank or store but due to DFS now one can buy these online and even the funds can transfer or withdraw directly from home with internet access. This not only increased sale and customers locally but also globally. It is needed to investigate how DFS are affecting such products and organizations.