Picture books for preschoolers sell just as well as lesbian poetry at this cooperative. Recognized in 2003 by Publishers Weekly as one of this country's last great academic bookstores, Seminary, which opened in 1961, carries an impressive array of nonfiction in its crowded maze of shelves. The tiny Newberry Library store stocks cartography, history, and genealogy titles, while vast 57th Street leans more toward general interest. All offer a 10 percent discount to members.