Chemical Information Sources/SIRCh/Deep Background Reading

SIRCh: Selected Internet Resources for Chemistry
Online Public Access Catalogs (OPACs) of Libraries with Major Chemistry Collections
Multisource

Credo Reference (formerly, Xrefer, the Web's reference engine) contains encyclopedias, dictionaries, thesauri & books of quotations from the world's leading publishers, providing a single source for factual information. Sources include Oxford University Press's A Dictionary of Biology, A Dictionary of Science, A Dictionary of Scientists, and The New Penguin Dictionary of Science

Dictionaries
Encyclopedias
Publishers' Catalogs
Textbooks
Monographs and Textbooks