Websites

Books Are Everything - Author/collector Graham Holroyd's site provides searchable database, pages on grading and reference books, more.

Grading the Condition of Vintage Paperbacks & Pulps - This eBay guide by benneson is a concise intro to the topic.

The Revolutionary Effect of the Paperback Book - Smithsonian.com - Clive Thompson's article provides some historical background.

Vintage Paperback Archive - Informative site includes list of paperback publishers, articles, cover artists, key authors, much more.