Krueger Books
- Offers Rare, signed and first edition.
- http://www.kruegerbooks.com/

Kay's Secondhand Books & Used Sheet Music
- Used non-fiction books and sheet music, listed in categories.
- http://www.kaysmusic.com/

Keeble Antiques
- Rare, antiquarian and out of print books, publishers end of line titles, deltiology, old photographs and antique maps. based in Dorset, UK.
- http://www.keebleantbks.co.uk/

Ken Sanders Rare Books
- Specialities include Edward Abbey, Wallace Stegner, B. Traven, Utah and the Mormons, and Modern First editions.
- http://www.ksb.com/

Kazoo Books
- Used books including hard cover and paperback, featuring more recent titles rather than old and rare.
- http://www.kazoobooks.com/

Keogh's Books
- Secondhand and antiquarian books. Search by author, title or keyword. Many out of print editions, specialising in arts and literature.
- http://www.keoghsbooks.co.uk/

Kolumb Internet Bookstore
- Used, rare, antiquarian and out-of-print books (including first editions) specialialties include the former USSR, Oriental languages, as well as art, ballet and illustrated books.
- http://www.kolumb.com/

Kloof
- Scholarly books from all times on the law, economics, history, philosophy and other sciences.
- http://www.dekloof.com/

Ken Spelman Rare Books
- Fine, rare, antiquarian, academic and out-of-print books. UK based, ships worldwide.
- http://www.kenspelman.com/

Ken Lopez - Bookseller
- Out-of-print and rare books, specializing in modern literary first editions.
- http://www.lopezbooks.com/

Kelmscott Bookshop
- Collectible, out-of-print, and scholarly books as well as search, book binding and restoration services.
- http://www.kelmscottbookshop.com/

Kane Books
- Scholarly and antiquarian books.
- http://www.kanebooks.com/