The Library Catalog (aka LibrarySearch) contains the records for many of the articles and books that are found in the various databases listed below, and it's a good starting place, but there are advantages to searching subject specific resources (such as the ability to specify a time period in Historical Abstracts), or using resources that allow you to search full text (such as JStor and Project Muse), or a database that has unique features that enable you to find connections within scholarship (Web of Science/Social Science Citation Index).
The Web of Science “Core Collection” includes the following:
Arts & Humanities Citation Index (AHCI)
Book Citation Index - Science (BCKI-S)
Book Citation Index - Social Sciences & Humanities (BCKI-SSH)
Current Chemical Reactions (CCR-EXPANDED)
Emerging Sources Citation Index (ESCI)
Index Chemicus (IC)
Social Sciences Citation Index (SSCI)