Wingate, Marcel, E., The Structure of Stuttering : A Psycholinguistic Analysis (currently out of print)
Wingate, Marcel (1999) Stuttering - A Short History of a Curious Disorder, Bergin & Garvey.
Wollock, Jeffrey (1998) The Noblest Animate Motion is a book about the history of communication disorders, with many historical references to stuttering.
Stuttering Foundation of America Online Store provides information about all SFA materials available for purchase.
If you are looking for an out-of-print book, you might try Bookfinder or Alibris may help you locate stores that have it. They may also help you find "used books" as will Books a Million, Half.com, ABE Books and Best Book Buys
Freely-available books are also linked to The Library