From Writing As A Second Career:
Some of my favorite books on writing, business, and marketing from other authors:
On Writing by Stephen King
On Becoming A Novelist by John Gardner
The Thirty-Six Dramatic Situations by Mike Figgis
Writing In An Age Of Silence by Sara Paretsky
Fiction First Aid: Instant Remedies for Novels, Stories and Scripts by Raymond Obstfeld
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On Business And Marketing
The Successful Author Mindset: A Handbook for Surviving the Writer's Journey by Joanna Penn (you can find Joanna's interview of me on writing, juggling multiple careers, and happiness as an author here)
How To Market A Book (Third Edition) by Joanna Penn
How To Write A Sizzling Synopsis by Bryan Cohen
The Prosperous Writer's Guide To Making More Money: Habits, Tactics, And Strategies For Making A Living As A Writer by Honoree Corder and Brian D. Meeks
I've also found the author business courses from Joanna Penn of The Creative Penn inspiring and useful.
(I'm an affiliate of Joanna's courses, which means I get a small percentage if you sign up through my link. I recommend all her materials, though, based on how much I've learned from her and how helpful I've found the information she shares.)