The history of science fiction is remarkably well documented. It's short, and many of the important people involved in it were writers; that's part of it. But a lot of it is that fandom has always been interested in its own history, and fandom is integral to the genre, especially in the early days. This provided both a market for professional publications, and a large and rich source of amateur publications.
The Way The Future Was: A Memoir
By Frederik Pohl.
Fred Pohl has played many roles in science fiction, including being a major author, and an agent, and a magazine editor. He was also in the right place at the right time -- New York City in the 30s. Many of the biggest names in science fiction came out of the Futurians there.
By Damon Knight.
Damon Knight chose to write specifically about the Futurians society in New York, so he can devote more time to it than if it were only a part of a complete autobiography. His views are interesting, especially taken together with the other people (especially Fred Pohl) who have reported on those events. I don't mean they disagree strongly; but you can see differing viewpoints.
Wonder's Child: My Life In Science Fiction
By Jack Williamson.
The John W. Campbell Letters
Edited by Perry A. Chapdelaine Sr., Tony Chapdelaine and George Hay.
The John W. Campbell Letters With Isaac Asimov and A.E. Van Vogt
If Hugo Gernsback invented science fiction, John W. Campbell set its modern form. Under his editorship, Astounding (later Analog) was the premier SF market in the world. He first published a remarkable number of the biggest names in the field. And he wasn't a passive editor; sometimes he was a very active participant in setting the final shape of the stories he published. Some authors resented this -- but this is widely believed to be the reason that Dune is so much better than any of Frank Herbert's other books.
No editor will ever again be this important to the field; it's impossible now, the field has grown too much, and has too much history. Appearing as he did very early on, Campbell was able to set his mark on the field permanently.
Campbell was apparently a quirky, opinionated, argumentative, man. No wonder he worked so well with so many major SF authors! He made people think. He made people argue their points.
He also tended to get enthusiasms, and would sometimes try to drive authors, and stories, in directions that the material, or the authors, just couldn't support. Especially later in life, he got into things like the Dean drive and ESP.
Basically, he was a bit of a crank. Was that always part of his personality? When he started editing, were space travel and atomic power just as much crank topics as the Dean drive was later?
There are apparently letters extant and even organized to fill additional volumes (one of which has been published, but have not read). Now, what I'd really like is the CD-ROM edition. I want to find all the letters to certain people, or mentioning certain topics.