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.