This study applies the bibliometric method to review research in collaborative learning in e-learning and analyzes the trends of research on this topic. Using quantitative tools of science mapping, 8,575 papers in the Scopus database, prior to and including 2019, were reviewed, tracing back to 1988. Retrospective analysis uncovers continuing trends in research by way of topic-related sequence and geographic differences in sub-topics by space; moreover, further analysis is undertaken on the structure of knowledge bases. This reveals that the journals of highest impact include "Computers in Human Behavior," "Computers & Education," and "Journal of Computer Assisted Learning," while the most impactful authors are Barolli, Caballé, Chen, Daradoumis, Dimitriadis, Li, Li, Sterbini, Temperini, Tsiatsos, and Xhafa. This paper concludes that the bibliometric method can target a broad range of research; topics related to applied science and emerging technologies are still to be studied. Research topics are cross-border, not limited to geographically close nations.