DC · May, 1968
1st appearance of Back-Up Metal Men; 1st appearance of Cobalt; 1st appearance of Darzz; 1st appearance of Gallium; 1st appearance of Iridium (Iridia); 1st appearance of Osmium; 1st appearance of Silver; 1st appearance of Zinc
The Amazing School for Robots
Writer: Otto Binder
Artist: Gil Kane