Lewis & Clark Libraries: Reference Shelf: Start Here

OED

The O.E.D. provides authoritative definitions and traces the usage of words from their first recorded occurrence to the modern period.

Gale Virtual Reference Library
A collection of full-text, multi-volume reference titles in a range of subject areas.
Oxford Reference Online
Electronic version of Oxford reference across a broad range of topics. Full-text.
Columbia Gazetteer of the World
A comprehensive encyclopedia of geographical places and features.