The Making of Star Trek, and several other sources. (The other sources may have been referencing TMoST, though.) If I remember right, CVN-65 may have been the latest and greatest at the time, but CV-6 had quite the illustrious history behind it.
I don't doubt that's true, but damned if I can find it in TMoST. I did see carrier names discussed as other starship names, Forrestal
mentioned wrt starship tonnage, and CVN-65 used for a size comparison diagram.
At least according to Memory Alpha, it's on page 164
. (I'll admit I don't have the book myself.