Encyclopedias are great for:
The Classical Studies division has a number of useful full text titles:
Hornblower, Simon and Antony Spawforth, eds. The Oxford Classical Dictionary. 5th ed. Excellent source. Covers biography, literature, mythology, philosophy, religion, science, geography of the classical world with bibliography.
Brill's New Pauly: Encyclopedia of the Ancient World. (in print in Olin Room 604-605 DE5 .N48 2002) Entries and articles have been updated to the current state of scholarship while continuing the tradition which started with the old. Entries offer easy, direct access to basic information - names, places, dates, objects - from all areas of Greek and Roman culture as well as their predecessors, neighbours and heirs.
Oxford Art Online provides web access to the entire text of The Dictionary of Art, ed. Jane Turner (1996, 34 vols.) and The Oxford Companion to Western Art, ed. Hugh Brigstocke (2001). Articles, and over 1,500 thumbnail art images and line drawings, extensive image links, and sophisticated search and navigation tools.
Routledge Encyclopedia of Philosophy. Excellent on all aspects of philosophy and history of ancient science.
Ancient Writers Greece and Rome. 1982 (Olin Reference PA 3002.A54) Grant, Michael, and Rachel Kitzinger. Civilization of the Ancient Mediterranean: Greece and Rome. 3 vols. New York: Scribners, 1988. (Olin Reference DE 59 C58 1988)
Encyclopedia of Greece and the Hellenic Tradition. 2000. (Olin Reference DF757.E53x 2000)
A genealogical chart of Greek mythology : comprising 3,673 named figures of Greek mythology, all related to each other within a single family of 20 generations. 2003. (Olin Library Reference BL785 .N44 2003 ++)
Encyclopedia of Greco-Roman Mythology. 1998. (Olin Reference BL 715 D56x 1998)
Early Greek Myth: A guide to Literary and Artistic Sources. 1993. (Olin Reference BL782.G21)
Encyclopedia of Ancient Dieties. 2000. (Olin Reference BL473 .C68 2000 +)
The Encyclopedia of Religion. 1987. (Olin Reference BL 31 E55+)
The Dictionary of Classical Mythology. 1986. (Olin Reference BL 715 .G86 1986)
Gods and heroes : a quick guide to the occupations, associations and experiences of the Greek and Roman gods and heroes. 1977. (Olin Reference BL715 .H29)
Funk and Wagnall's Standard Dictionary of Folklore, Mythology, and Legend. 1972. (Olin Reference GR 35 F98 1984)