Below is a video recorded at the U.S. Copyright Office in early 1987, at an event for staff, where Waldo Moore, who had been at the Office since 1951, provided some history of the Copyright Office, and discussed some of the individuals who had held the position of Register of Copyrights. Moore retired the year before he gave this talk, and William Patry has a nice piece about him on his now-defunct blog. Much of the material Moore includes in his talk has, to my knowledge, not been published.
I will caution, for those seeking details on recent events, the Moore is quite circumspect about events from 1970 on, preferring to speak about earlier eras. Looming in the background of the talk was George Cary’s appointment as Register in 1971, which led Barbara Ringer to sue and that appointment to be vacated, at which point George Cary retired and Barbara Ringer was named Register. George Cary is specifically mentioned as being in the audience for this talk, which would make discussion of the controversy impolitic (it probably would have been even without him in the room).