The story was first published in the magazine Unknown for June , 1939 .
The story was first first appeared in book form in de Camp 's collection The Wheels of If and Other Science Fiction ( Shasta , 1948 ) .
The story was first published in the magazine Unknown for June , 1939 and first appeared in book form in de Camp 's collection The Wheels of If and Other Science Fiction ( Shasta , 1948 ) .