Not out yet, but you can now pre-order the forthcoming Vintage Fashion Sourcebook by Cleo and Mark Butterfield, which is published by Carlton Books on 12th May.
The people behind the book are the owners of C20 Vintage Fashion, which both hires out and advises on vintage fashion. The book itself, covering a fairly modest 64 pages, claims to offer a 'decade by decade look' at 20th century clothing, as well as pointers on sourcing and caring for original vintage pieces. The book also covers 'key looks' from the different eras.
Probably not the most in-depth book around, but certainly sounding like a good introductory guide, with a budget price of just £4.49.