Out of Print and Rare Books
AcqWeb Directory of Rare and Antiquarian Book Vendors
AddALL Used and Out of Print Search
Advanced Book Exchange (Abebooks)
Alibris
Antiquarian Booksellers' Association of America
Antiqbook--European out-of-print site
Bibliophile.net
BookFinder.com
Georgia Antiquarian Booksellers Association
TomFolio.com
USBE Back Issues Shelf List--online list of journal back issues
Your Old Books--FAQ about rare books and book values