Google Scholar is a very unspecialized database. It's multidisciplinary and wonderful, no question. However, our subscription databases cover more materials and resources, are better indexed and described, and for a longer period of time than does Google Scholar. So if you want a really thorough search on a subject or a complete bibliography of an author, you should consult with our databases in the relevant subject(s) or a Librarian subject specialist!
The 2 best large multidisciplinary databases, to which Princeton University Library subscribes are:
Web of Science (1900+)
Both offer forms of citation searching. There is more value added as in indexing for field searching, date ranging, format, type of publication, keywords, relational/syntactic subjects, language, authors, affiliations, and more.