Thanks. I got an answer in email already.
I have a couple of old Ace paperbacks, and I was looking at the list. Only the later Dragon books are listed, but it doesn't say that they're the later books. The only hint was the cover of what seemed to be the first one talking about the "triumphant return".
Those books went back into Ye Old Packing Crate of Paperbacks to await my locating the beginning of the series. (Actually, I just picked up "Category 7" from the library, so it'll be a while.)