CiteSpace
A widely used tool for visual exploration of scientific literature.
..., for example, PubMed, CNKI, ProQuest Dissertations and Theses. CiteSpace reveals how a field of research has evolved, what intellectual turning points are evident along a critical path, and what topics have attracted attention. CiteSpace can be applied repeatedly so as to track the development of a field closely and extensively.
The e-book How to Use CiteSpace explains the design principles and functions along with illustrative examples in more detail:
https://leanpub.com/howtousecitespace