Here's a handful of books on pre-code horror comics, one of my favorite things. Clicking the links will send you to Amazon. Happy reading!
The Horror! The Horror! Comic Books the Government Didn't Want You to Read!
Four Color Fear: Forgotten Horror Comics of the 1950s
The Ten-Cent Plague: The Great Comic Book Scare and How it Changed America
Ghastly Terror: The Horrible Story of the Horror Comics
Tales of Terror: The EC Companion
Horror Comics: The Illustrated History
A Haunt of Fears: The Strange History of the British Horror Comics Campaign