These special subject encyclopedias are all in the Reference section on the first floor of the library
World Eras. Volume 6: Classical Greek Civilization 800-323 B.C.E.
REF D 20 .W67 2001
Oxford Encyclopedia of Ancient Greece and Rome (7 volumes)
REF DE 5 .O95 2010
Encyclopedia of Ancient Greece
REF DF 16 .E52 2006
Oxford Classical Dictionary. 3rd. ed
REF DE 5 .O9 1996
Greek Thought: A Guide to Classicical Knowledge
Ref DF 78 S2813 200
This volume has a section with substantial entries on major figures in Greek thought.