This resource searches the holdings of new and out-of-print book databases and presents a combined result. Databases searched include Advanced Book Exchange, Powell's Books, and others.

This multi vendor search engine is particularly useful for non-North American imprints.

This site claims it is the world's largest source of out-of-print books with over 13 million titles.

This reseller taps into the holdings of over a thousand small out-of-print dealers and re-sells their titles directly and via services such as Amazon.com.

Metasearch engine for rare and out of print materials, including maps.

The ABAA Booknet specializes in rare and antiquarian books, maps and prints.

This megabookstore, based in Portland, Oregon, has a immense collection of technical books.

This website focuses on textbooks and provides price quotes from multiple textbook retailers.

Based in Ohio, this company buys and sells used scholarly books.