3 Lost Pulp Sci-Fi Masterpieces from 1930s to 1960s

There was a time when the world was filled with realistic hope about a future driven by science and technology.
Cynicism, malaise and boredom hadn't yet taken over the Sci-Fi pulp of the 1930s to the 1960s.

Here are 3 vintage masterpieces I have rediscovered, which span these 920 pages, including the original awe-inspiring illustrations.
I hope you thoroughly enjoy the "Galaxy Primes," "The Skylarks of Space" and "Spacehounds of IPC."