Anchor Books was and is a trade paperback imprint of Doubleday. This book, though mass market paperback sized, has heavier-than-usual cover stock, and a higher-than-usual cover price ($3.50, at a time most mm paperbacks ran $1.50), giving it the flavor of a basic textbook, though Spinrad does not use that term. He does provide an introduction to modern sf, and three intermediate essays for the book's three sections: "The Golden Age", "The Postwar Awakening", "The Full Flowering". And he provides an appendix of "additional significant works", novels especially by authors who couldn't be included in this book.