Thanks for the suggestions, which were excellent. The marriage license does not show the parents, and they were married by a justice of the peace, so no church records. And the online Nagykanizsa Civil Records stop three years before his birth, unfortunately.
We've tried getting his SS5 from Social Security, which does include his parents names--but they were blocked out for "privacy" concerns! We were told that we couldn't get the information without proof that they were dead (which if we had, of course, we wouldn't need the information from the SS5!). They apparently think that the parents of someone born in 1920 might possibly still be alive . . . kinda unlikely, don't you think?
Anyway, thanks for the suggestions.