M. Hofferber Books: Specializing in nature, science, how-to, guidebooks, cookbooks and western Americana.
Mackus Company: Acquisition and sale of illuminated manuscripts and historical legal documents. Statement of authenticity included.
Madden Books: Rare, used antique and out of print books, specializing in politics and history including Chinese, Cuban, Soviet and Socialist publications.
Maggs Rare Books: Multi-speciality rare and antiquarian booksellers.
Maremagnum Librorum: Antique, old and out of print books; in English, French, German,Italian and Spanish.
Maxwell's Bookmark: Rare and out of print books, including California, Scottish history, genealogy, illustrated books.
Meetinghouse Books: Old, used and out-of-print bookshop; includes world history, literature, cultural studies, arts, and natural history.
MemoraDelia: Used science fiction, fantasy and horror books. Plus collectibles, independent press.
Michael Ginsberg Books: Western Americana, American History, Canadiana, Voyages and Travel, Bibliography and Reference books.
Michael Treloar Antiquarian Booksellers: Particular enthusiasms are modern first editions, cricket ephemera, and North Australiana.
Min's Book Cellar: Gently used books, including homeschooling, childrens, parents, families, christian, fiction and nonfiction.
Mitzi Witch's Used Books: Fiction and non-fiction in a variety of areas.
Mockingbird Books: Used bookstore with used, rare, out-of-print, and hard-to-find books in all subject areas.
ModernRare: Rare, out-of-print, and signed books for collectors, specializing in modern first editions, photography, and one-of-a-kind books.
Moe's Books: Catalogs of out-of-print, new, and antiquarian books in all subject areas updated weekly.
MojoMax Books: Rare used books; including classical literature, art, history, Americana, and modern first editions.
Molly's Bookstore: Out-Of-Print, Rare, and used books.
Motte And Bailey Booksellers: Specializes in history and science fiction works, variety of general stock as well.
Mr. Kolk Raamatuantikvariaat: Rare and old books from Estonia. Maps, postcards and prints also available.
Mumfordbooks: Secondhand rare and old books; first editions, out-of-print.
Mystical Unicorn: On-line shopping for used books, bibliographies and author information.