I just got two new references in the mail, after having decided that I desperately need to improve my library. The Coinage of the Roman Republic - Edward Sydenham, 1976 reprint Alexandrian Coins - Keith Emmett, 2001 Plus, I found an excellent website that offers portions of the British Museum Catalogue of Greek Coins, still a standard reference despite being written in 1876. http://www.snible.org/coins/bmc/
Ard, You should check out the latest CNG auction #79. I'm don't know much of any about ancient coins or books about them but it appears to me that they have a lot of numismatic reference books/literature on ancient in their auction.