In 1954, AASLH sold the magazine to a quartet of writers and editors from Time, Inc. including James Parton, Oliver Jensen, Joseph J. Thorndike and founding editor Bruce Catton, the Pulitzer Prize-winning historian of the Civil War. They formed the American Heritage Publishing Company and introduced the hardcover, 120-page advertising-free "magazine" with Volume 6, Number 1 in December 1954. Though, in essence, an entirely new magazine, the publishers kept the volume numbering because the previous incarnation had been indexed in the "Reader's Guide to Periodical Literature". Each year begins in December and continues through the following October, published every other month. For example, Volume XXV issues are December 1973, February 1974, April 1974, June 1974, August 1974, and October 1974. December 1974 begins Volume XXVI.