P. Scott Brown, Bookseller
Bookstore with general and specialist lists.
http://www.downtownbrown.com/

Pacific Rim Used Books
A variety of subjects, including books about Pacific Rim nations.
http://www.pacificrimusedbooks.com/

Pageant Book and Print Shop
Used and rare books.
http://www.pageantbooks.com/

Pages Past
Collection of old, used, and rare books listed by subject.
http://www.pagespast.com/

Paladin Books
Used, out-of-print books and magazines; hard to find titles including men's magazines.
http://www.paladinbooks.com

Palette and Print
Offering vintage, used and rare books.
http://www.paletteandprint.net/index2.html

Paperbacks.com
Specializing in a variety of used titles.
http://www.paperbacks.com/

Papermill Books
We specialize in quality used and hard-to-find books, primarily non-fiction for adults and children.
http://www.papermillbooks.com/

Payson Hall Books
Out-of-print, rare and antiquarian books; strengths in the books about Ireland and the Irish, America (especially New England), Architecture and Art.
http://www.oldbooks.com/

Pecan Tree Books
Rare and antique books; children's books, first editions, signed and out of print books.
http://www.pecantreebooks.com/

Pellbooks
Hard-to-find books with an emphasis on German and Austrian literature. Over 6000 titles in 35 different catalogs.
http://www.pellbooks.com/

Peter Grosell Antiquarian Bookseller
Old and rare books. Site in English and Danish; many books listed only in Danish.
http://www.grosell.dk/

Peter Harrington
Travel and voyages, natural history, children's books, fine bindings. Based in London UK.
http://www.peter-harrington-books.com/

Peter J. Hadley Bookseller
Rare and academic books, catalogued by subject and author.
http://www.hadley.co.uk/

Phantom Books
Used, rare and out of print books with an emphasis on the unusual.
http://www.phantoms.com/

Philadelphia Rare Books and Manuscripts
Early Printed Books, Substantive Manuscripts, U.S. and Latin Americana, Hispanica, Histories and the History of Ideas, Travels, Law, Religion, and Bibles (all prior to 1820).
http://www.prbm.com/

Pinacle Books
Antique books for sale, sorted by category.
http://www.pinaclebooks.com/

Pioneer Books
Antiquarian and secondhand books including modern first editions, children's, ephemera, Victoriana, Australiana, sports, music, maritime, military, art and Asia.
http://www.pioneerbooks.com.au/

Pistil Books
Offering various categories of used and out-of-print books, blank books, and journals. Also offers book searches.
http://pistilbooks.net/

Plaza Books
First editions, literature, history, Western Americana, wine and food books, and general stock.
http://www.plazabooks.com/

Powell's Books
New, used, and out of print books; many categories with detailed descriptions and illustration of selected books.
http://www.powells.com/

Princeton Antiques Bookservice
Literary procurement and research specialists for rare, antique and out of print books.
http://www.princetonantiques.com/

Published Page
Searchable used and rare bookstore, also offers book locater service for titles not in stock.
http://www.publishedpage.com/

Puppet Press
Original eBooks, rare and used books.
http://www.puppetpress.com/

The Philadelphia Print Shop
Atlases, geographies, Americana, color plate books, illustrated travels, gift books, histories, and other rare books from the sixteenth through the nineteenth century.
http://www.philaprintshop.com/rarebook.html