Adventure Comics #306 - G-1.8

Cover pencils by Curt Swan, inks by George Klein. The 5th Dimensional High-School! starring Superboy, script by Otto Binder, art by George Papp; Mxyzptlk plays pranks on Smallville in order to do well in his 5th dimensional practical joking class. The Legion of Substitute Heroes--Tales of the Legion of Super-Heroes, script by Edmond Hamilton, art by John Forte; A group of rejected applicants band together as the Legion of Substitute Heroes and thwart the Plant Men's scheme to take over the Earth; First appearances of Polar Lad, Night Girl, Stone Boy, and the Chlorophyll Kid.