dale mmpbs were a strange breed: p/b format, but mostly distributed as though they were magazines. they were published by joel davis, who'd launched the successful sf prozine, isaac asimov's science fiction magazine - sometimes abbreviated to "iamsf"° - and later, the less-successful, highly-illustrated and larger, thinner, saddle-stapled format isaac asimov's science fiction adventure magazine, and seems to've used dale books 1977-79 as a means of using first reprint rights to stories bought for his magazines, where these were included in the licences, and also to publish mmpbs'of about a dozen or so sf & fantasy novels, etc, the merkin rights to which were presumably additionally acquired.
i don't know how, where or why the rights to this novel - and the short story - were picked up; but that's how come dr. iamsf's mug appears on its front cover.
° - the first three quarterly issues' covers of which were two side, and one full-frontal mugshots of the good dr. a. (after which joel davis eschewed the opportunity of displaying the back of asimov's head - alas - but shrunk it down - leastways in portrayal - considerably. . .
"iamsf" was not edited by isaac asimov, but by professional editor george h. scithers from spring 1977 launch issue through 1982; and thereafter by various other editors, notably including shawna mccarthey.
dale books mmpb first printing, not first mmpb edition
title short novel also published as "cosmic manhunt" (1954), q.v.
"perpetual motion" (originally "wide-open planet" in future combined with science fiction stories 9-10/1950) is a ~46pp viagens interplanetarias novelette.
cover and interior b+w art by jack gaughan (credited)
cover price $1.50
224pp. including titles, indicia etc, end pp. advertising