British Tokens and Their Values Book

The is the best one-volume work on Roman provincial coinage, which Sear calls Greek imperial. The work may seem a bit dated, and that is certainly the case when it comes to the valuations, but the true value of the book is that it covers virtually every coin-minting entity in the empire, from J. Caesar to the later 4th century. It is by no means comprehensive, since emperors such as Septimius Severus and Gordian III has a huge range of issues, but it gives a very good sampling of what's out there. I highly recommend this book for ANYONE collecting Roman provincial coinage, whether beginner or advanced.