On sale date from an ad in Star Spangled War Stories (DC, 1952 series) #162 (April-May 1972) and Comic Reader #81.
Lettering credit from reprint in Legion Archives. As Dave Cockrum explains in the foreword to that volume and elsewhere, the art credits were flipped on this story because he was a novice and the editor did not want to offend the veteran Murphy Anderson.
First Cockrum art on Legion of Super-Heroes feature.
Letters from: Illona R. Arywitz, Richard H. Morrissey, Laurie Williams, Jo Davoli.