This gigantic book by Pamela Golbin (author of the excellent overview "Fashion Designers") really tells the story of two houses of Balenciaga - the original, helmed by the great Cristobal Balenciaga, and the modern-day couturier. I'm not a huge fan of the 2000's Balenciaga lines, so I won't say much about them here - though, in all truth, this book does cover modern-day Balenciaga quite thoroughly for anyone who's interested.
The real heart of the book for vintage-fashion mavens, however, is the first half of the book, detailing the work of the illustrious Senor Balenciaga. The gentleman was probably the finest designer of the "New Look" era after M. Dior himself, and worked for much longer than Dior did. He excelled particularly, in my own opinion, at lush, silken, flowing gowns, which are copiously - and beautifully - detailed here. It's all here; biographical information, design sketches, behind-the-scenes photographs, catwalk shots. If you've been having trouble finding Marie-Andree Jouve's huge (and very expensive) Balenciaga retrospective, this is a perfect way to satisfy your desires!