Early SF: The Pulps and Space Opera
The Pulps | Hugo Gernback | Space Opera | E. "Doc" Smith

The Pulps

•  A Brief History of  the Pulps from Pulp.net
• More History of the Pulps from Adventure House Books
• A BRIEF HISTORY OF SCIENCE FICTION & PULP MAGAZINES
• A FAQ on Pulps from alt.pulp
• Reminiscing About Reading Pulps
• The Pulp Links at Pulp.net
• The Pulp Zone on Amazing
• The Pulp Zone on Astounding
• The H.P. Lovecraft Archive

• Sam Moskowitz's Intro to Gernsback
• Chapter One of Ralph 124C 41+
• Chapter One of Ultimate World  (caution--somewhat sexually explicit)

Space Opera

•  Definitions and Reading Lists at The Ultimate Guide to SF
• A Nice Definition of CLassic Space Opera from Orion's Arm
• "Exploding Worlds": Allen Varney's History of Space Opera
• Space Opera and Capitain Video
• Huge List of Space Operas

• The Lensman Series
• Summary of the Series by Publisher
• Craig Engler's Intro to Lensman and Triplanetary (explains historical context of series)