Here is the latest version of the list I did a while back of all of the Cobra books I'm aware of, along with a couple of links to sellers who might have used copies in stock (some of them are out of print):
-Essential AC Cobra, by Rinsey Mills
-Original AC Ace and Cobra, also by Rinsey Mills
-AC Cobra, also by Rinsey Mills
-The SAAC World Registry, editions One and Two
-AC Cobra 1962-69, a Brooklands book compiling old road tests and magazine articles
-AC Cobra Gold Portfolio, another Brooklands compilation
-Cobra, the Complete Story, by Brian Laban
-Automobile Quarterly vol 14-3, which has a Cobra article
-Automobile Quarterly vol 16-3, which has a Shelby article
-Automobile Quarterly vol 22-3, which has a great article on the 427 cars
-Carroll Shelby's Racing Cobra, by Friedman and Christy
-The Cobra Story, by Carroll Shelby
-Ford Cobra Guide, by Bill Carroll
-Road and Track on Cobra, Shelby, and Ford GT40, another Brooklands compilation
-Shelby American Guide, by Rick Kopec
-Shelby's Wildlife, by Wallace Wyss
-Daytona Cobra Coupes, by Pete Brock et al.
-Cobra: The Real Thing, by Trevor Legate
-Shelby Cobra, by Dave Friedman
-Remembering the Shelby Years, by Dave Friedman
-The Cobra-Ferrari Wars, by Mike Shoen
-Cobra Super Profile, by Grainger
-Cobra, by Beki Adam
-Classic AC's, by John McLellan
-AC Heritage, by Simon Taylor
-Shelby, by Steve Statham
-AC (Cobra) Autohistory, by F. W. McComb
-Shelby Buyer's Guide, by John Lamm
The Rinsey Mills "Original AC Ace and Cobra" book has some pretty good coverage on the 427 cars, if you're looking for detail shots of original cars. If you're looking for history, the Automobile Quarterly 22-3 article is very good.
The best source I've found for tracking down the out-of-print ones (besides eBay) is found at http:
www.abebooks.com/home/TEW/
The in-print ones can usually be found at
www.motorbooks.com or
www.ewa1.com.
Bob