Reddit mentions of Screenwriting is Rewriting: The Art and Craft of Professional Revision

From previous comments:

TV Calling has a lot of info.

Spec Writing Rules

The Podcast

Jane Espensons Blog is also invaluable

From a thread two weeks ago

• Writing the Romantic Comedy
  by Billy Mernit
  
  
• Not on Kindle, which is my main gripe. Very useful structure.
  
  
• Writing the Comedy Blockbuster: The Inappropriate Goal
  by Keith Giglio
  
  
• Save the Cat but focused specifically on writing comedies. Really focuses on making sure you derive maximum conflict from your protagonist meeting your premise.
  
  
• Elephant Bucks: An Insider's Guide to Writing for TV Sitcoms
  by Sheldon Bull
  
  
• A decades long professional writer and showrunner tells you how to write a sitcom. You're dumb if you wanna write sitcoms and haven't cracked this open yet.
  
  
• How to Write Funny: Your Serious, Step-By-Step Blueprint For Creating Incredibly, Irresistibly, Successfully Hilarious Writing
  by Scott Dikkers
  
  
• Again, a professional explains how he works. Dikkers was head writer on The Onion for years and years.
  
  
  
• Writing the Pilot
  by William Rabkin
  
• Again, a veteran showrunner explains what he knows.
  
  
• Screenwriting is Rewriting: The Art and Craft of Professional Revision 1st Edition
  by Jack Epps Jr
  
• Fucking gold. I'd read it even before you finish a first draft.
  
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  Also, this subreddit has a Wiki.