Loeb Classics
Image from Loeb Classics website
LOEB: Ancient history, with its paucity of sources, is unusually dependent on the writings of ancient Greek and Roman authors which have survived to our present, sometimes only in fragments. While reading them in their original languages is superior, for the rest of us, “[t]he Lobe Classical Library has been a mainstay of anglophone Classics for many years." Long a familiar mainstay of library collections in its iconic undersized hardback editions (“Red for Romans/Green for Greeks”), it has now been digitized. For more information see : Helma Dik, “Review Essay: On First Looking into the Digital Loeb Classical Library.” Classical Journal 11, 4 (Apr.-May 2015): 493.
Alkek has the full digital collection here.
Library also owns print copies, check the online catalog for specific titles.
Sample Search Video
Here's a video showing how to do a search in Loeb Classic Library.
Note: The demo of the search starts at about 3:23 into the video so, start there.