This run of issues were the first ones I remember getting as a kid. My mom used to take me to Woolworths a lot and she would let me buy the Whitman three packs of comics they would sell. Sometimes they would be several issues in a row of a particular title. I might be wrong, but I think I got these three issues of Superman in one of these packs. All three covers were by Rich Buckler and he kept Garcia Lopez' style intact. These are issues #'s 324-326, June-August, 1978.
Of course, all these issues have beautiful Swan art on the inside. These books are just some small examples of how DC was great in the late '70's.