The Marvel-DC Crossover by Joe Kubert That You've Never Seen
The comic itself was commissioned by World Color Press in 1977 to celebrate their open day. World Color had been printing comic books since 1940 and the magazine showcased their history with photos and histories. Sadly World Color doesn't exist anymore having been bought out not that long ago, but, in it's day, it printed virtually every American comic book that was sold on the market.
Seeing Joe Kubert's art on these characters, even as a throwaway project, is fascinating. Kubert's art career at Marvel was mainly restricted to a few projects, none of which involved the characters that he penciled and inked here - although the art does show signs of having been assisted, but the cover is pure Joe Kubert. Some of the pages were designed to be double page spreads, but, well, you can't have everything. Feel free to take a punt at the art credits.