Fifty-two years ago, Eugene Garfield envisioned the potential powerful function of citation indexing in science, and developed the theory and application of citation analysis with the evaluative index of impact factor. With the creation of Science Citation Index, Social Science Citation Index, and Arts and Humanities Citation Index, citation analysis has become a widely used tool for retrospective and up-todate literature research, identification of visible scholars in a specific subject and mapping of intellectual structures of a discipline, and measurement of impact for justifying tenure and funding decisions in the academic and scientific community. With the development of information technology, all three citation indexes were incorporated into the Web-based citation database Web of Science (WoS). Prior to the Internet age, WoS has been the sole research tool for citation tracking