I am looking for the same encyclopedia. Important characteristics: relatively small size, white-cream color with green spine, classic novel book summaries in back, and I believe the volumes were not strictly by one letter per volume but overlapped. For example, volume 1 might be, for example, Aardvark to Ant, and then volume 2 might be Anteater to Bolivia, etc, Not 100% sire on that…
This is something from, say, the mid 60s to early 70s. It may have been sold in supermarkets, it may have been associated with Readers Digest, not sure.
At one point, I thought it may have been the Student’s Merit - but it is not. Currently, I’m looking at Funk and Wagnalls and American People’s - but I’m skeptical, since I cannot find any description noting the book summaries and online pictures of volumes for sale do not clearly show the color scheme (although that may differ from year/edition)
World Book Encyclopedia at the time was cream with a green spine. We had a set from the 1960s in our house.
I don’t remember who made them, but I do remember encyclopedias being sold in the local supermarket. They gave you the first one for free. After that, they had a different one that you could buy each month. You had to be a loyal customer (at least loyal enough to stop by once per month) to buy an entire set. That also spread the cost out over a couple of years, so you didn’t get the sticker shock of buying an entire encyclopedia set at once.
Cream with a green spine wasn’t exactly an uncommon color back then.
The years before that were brick-red with blue- my parents used to have my father’s old set from when he was a boy- they had the ‘year books’ for about 7-8 years, and the last couple in the 1960s were green/cream.
When my pop croaked in the 90’s there was a complete set of them in his den that we cleaned out. The chapter on Richard Nixon had him listed as President 1969- so I assume they were published before 1974.
I vaguely remember my parents getting these at a grocery store (Sentry? Kohls? National? ) They had a weird off-white-cream-gold colored cover with the volume in a red band about an inch wide.
Slight hijack: there was a laundry soap powder that came with a wine glass inside the box that today you can get at the Dollar Tree for a buck. Plus there were Green Stamps for buying other shit and real prizes inside of kids breakfast cereals. The 60’s and 70’s were pretty neat for consumers, if you ask me!
HERE is what the encyclopedia(s) we took out of my old mans den looked like. Very popular in the early/mid/late 60’s. May or may not be what the OP is looking for. They were sold at grocery stores at that time, though.