The Oxford Encyclopedia of Ancient Greece and Rome is the clearest and most accessible guide to the world of classical antiquity ever produced. Available as eBook or physically in the reference collection (in-library use only).
Brill's New Pauly is the authoritative reference work for the ancient world. The Antiquity section is devoted to Greco-Roman antiquity, ranging from the second millennium BC to early medieval Europe. Special emphasis is given to the interaction between Greco-Roman, Semitic, Celtic, Germanic, and Slavonic cultures, and ancient Judaism, Christianity, and Islam.