Dick Giordano in an email to the indexer has confirmed that he inked this cover, and suspects that he pencilled it based on a layout from Carmine Infantino. However, it also seems to have a Curt Swan look; particularly Green Lantern (note the finger separation). Anthony Tollin told Tony Isabella in November 1980 that he colored this issue.
Per Michael Grabois, Joe Staton and Steve Mitchell both confirmed the art credits at a convention, signing Michael's copy. The Comic Reader #191 (May-June 1981) listed Frank McLaughlin as the inker.
Anthony Tollin was the source of the coloring credit (via Tony Isabella, November 2012).