Bartelby's is a good source for looking up quotes. Other sources are found in the reference area in the PN call number area.
A couple of examples are:
- Bartlett's familiar quotations: a collection of passages, phrases, and proverbs traced to their sources in ancient and modern literature by John Bartlett Call number: REF PN6081 .B27 2002b
- The Oxford dictionary of literary quotations edited by Peter Kemp Call number: REF PN6081 .O89 2003