The primary database for locating scholarly work in Greek & Roman Studies.

Now in its 4th edition, the OCD is a scholarly mini-encyclopedia of people, events, places in the classical world. Signed articles. Some bibliography. It's a great way to identify good editions of primary texts. The print volume is in the Reference Collection at DE5 .O9 2012. Earlier editions are in the circulating collection at the same call number.

Comprehensive overview of the major cultures of the classical Mediterranean world—Greek, Hellenistic, and Roman—from the Bronze Age to the fifth century CE.

The standard encyclopedia that covers the ancient world from the prehistory of the Aegean to late antiquity. The online edition is in both English and German. For the print versions, see: Der neue Pauly: Enzyklopadie der Antike. Stuttgart : J.B. Metzler, c1996- (complete in 16 vol.).
Location: Reference DE5 .P34 1996
And also the English translation: Brill's New Pauly: encyclopaedia of the ancient world. Hubert Cancik and Helmut Schneider, eds. Leiden ; Boston : Brill, 2002- .
The English edition is divided into two print editions:
Antiquity (Location: [Reference DE5 .P3413 2006]
Classical Tradition (Location: [Reference DE5 .P34213]
An earlier print edition is also still useful:
Paulys Real-Encyclopadie der classischen Altertumswissenschaft, neue Bearb.. 24 vols, 10 vol continuation, 15 vol supplement. Stuttgart: Metzler, 1893-1978.
Location: [Main DE 5 .P33]