Some of the reprinted material was abridged, but despite this, "Famous Fantastic Mysteries" did an important service to its readers by making works available that had been long out of print, and which in some cases had only been previously published in the U.K., making their appearance in the magazine the first chance many subscribers have had to read them. Some original material also appeared after Popular acquired the magazine. Contributors who published original stories in "Famous Fantastic Mysteries" included Henry Kuttner, Ray Bradbury, and C. L. Moore. Arthur C. Clarke's story "Guardian Angel" appeared in the April 1950 issue; it was later turned into the first section of his novel "Childhood's End". Mary Gnaedinger was the editor of "Famous Fantastic Mysteries" for all 81 issues. The magazine was launched as a bimonthly in September 1939, and was converted to monthly from the second issue, in November 1939. The May 1940 issue was followed by August 1940, which began a bimonthly sequence that lasted until June 1942, which began another monthly sequence that ran through the end of 1942. The next issue, March 1943, was followed by a September issue that inaugurated a quarterly sequence that ran until December 1945, which began another bimonthly run. This lasted until the final issue in June 1953 with only two irregularities: October 1950 was followed by January 1951, and July 1951 was followed by October 1951. "Famous Fantastic Mysteries" was published by the Munsey Corporation until the end of 1942, and by Popular Publications, thereafter. The magazine was initially 128 pages long. This was cut to 112 pages with the October 1940 issue, and then returned to 128 pages for the June 1941 issue. From June 1942 to March 1944 the page count was 144; it was cut to 132 in June 1944 and again to 112 in January 1951, where it remained until the end of the run. The price was 15 cents throughout, except for the period from October 1940 to April 1941 during which it was 10 cents. "Famous Fantastic Mysteries" began as a pulp, and remained in that format throughout its run except for a brief experiment in 1951 in which it was reduced to large digest size. A Canadian reprint edition, with identical contents and dates, began in February 1948, from All Fiction Field, Inc.; in October 1951 the publisher became Popular Publications, Toronto, but this was just a name change rather than a change of ownership. The final Canadian issue was dated August 1952; these issues were half an inch longer than the U.S. versions.