Abebooks.com: Offering new, used, rare and out of print books, textbooks, and ephemera. Represents a wide variety of independent booksellers located throughout the world.
ABooksearch.com: Searches databases of participating booksellers.
Antiquarian Books in Scandinavia: Search the databases of the Scandinavian members of ILAB, International League of Antiquarian Booksellers.
Ardis Online Database: Searchable database of secondhand books from UK booksellers.
Biblio.com, Inc.: Searches databases of associated independent booksellers worldwide.
Biblion.com: Antiquarian and rare books from primarily UK book dealers available on a searchable database.
Bibliophile: Multilingual book search engine.
Bibliopoly: Multilingual, international search for antiquarian and rare books.
Big Words: Compares textbook prices at four stores - buying or selling.
Book Avenue: Search affiliated booksellers for out-of-print, used, rare and antiquarian books.
BookSearcher.org: Large online database of used, rare, hard to find, out of print, antiquarian and collectible books.
Cover to Cover Antiquarian Books: Offering a range of antiquarian, second hand and out of print books.
Library Book Sales: Matching book buyers with quality books that have been donated to libraries or are duplicate copies, monographs or surplus materials. Ex-libris titles are discouraged but not excluded. Library types participating: public, private, institutional, special collections, educational, foreign or domestic.
TomFolio.com: Searchable database of used, rare and collectible books from a group of booksellers.
Used Book Central: Searches the stock of affiliated dealers in the US.
Used Books Search: Search for used, rare and out of print books.
Wantedbooks.com: Comparison search capabilities for finding rare, used and out-of-print books from many independent sellers.
ZVAB: Search for old, rare and out-of-print books. Access to many bookstores. Bilingual, English and German.