Dupre, it is very possible that your first hunch is correct. TimeLife publishes, or did publish, many different sets of books on history, art, WWII, current events, science, and you name it. A person could subscribe to a given series and receive a book every month.
Hi, Hazlitt. Yep, I saw TimeLife's current series, it looks like a good set and reasonably priced, and I do remember my dad having some of those sets on the shelf. I was lucky to have access to such a terrific library growing up. My mom's mother had been an English teacher, so literature and drama was represented well, too. I don't know WHERE I'll put any new books and cannot bear to part with any I already have, but I do need more current selections and more on current events. <sigh>