To the best of my knowledge all books are available online at
Barnes & Noble Booksellers and Amazon.com

Ferret & Ferreting Handbook
James Mckay
Feb. 1994
ISBN# 1852237724
Hardcover

Biology and Diseases of the Ferret
James G. Fox
Jan. 1988
ISBN# 0812111397
Hardcover

Rumor has it that Dr. Fox will have an updated edition out sometime in August 1998

Ferrets, Rabbits & Rodents: Clinical Medicine and Surgery
Elizabeth V. Hillyer, Katherine E. Queensberry
Jan. 1996
ISBN# 0721640230
Paperback

A Practical Guide to Ferret Care
Deborah Jeans
Aug. 1996
ISBN# 0964258919
Paperback