Golden Age of Science Fiction
In the history of science fiction, the Golden Age is the period in which the genre is considered to have matured in American science fiction magazines, in particular Astounding Science Fiction; the period is usually referred to as the Golden Age of Science Fiction (as a whole), though sometimes more specifically as the Golden Age of Astounding. Its beginning is marked by John W. Campbell's assumption of the editorship of the magazine in the late 1930s.
Source: Wikipedia — Golden Age of Science Fiction (CC BY-SA 4.0)