In 1970, the work was slightly revised, but not sufficiently to warrant a separate ISFDB title record.
The earliest published version was a 9-part serial in Other Worlds Science Stories, October 1952 to June 1953.
As of 2019-12-09, Amazon.com provides a "Look inside" the 1970 Dover edition that shows the one-page, three-paragraph "Preface" (L. Sprague de Camp, 1970).
- The entire first paragraph:
"This book was originally written in 1948. After one publisher who had contracted for it failed, it was published serially in the magazine Other Worlds Science Fiction in 1952-53 and then published (with revisions) as a clothbound book by Gnome Press (New York) in 1954."
- The second paragraph concerns the "number of minor factual and typographical errors", identifying three "main additions".
- The third paragraph contains acknowledgments.
- "First Edition" on copyright page.
- According to Laughlin & Levack, De Camp, Underwood-Miller, 1983, there are two bindings, one in gray cloth, and this one in mottled green paper boards.
