Here are craft book suggestions from the Facebook Group The Playwright Connection.

• Dramatists Toolkit, The Craft of the Working Playwright by Jeffrey Sweet

• The Art of Dramatic Writing by Lajos Egri

• The Art and Craft of Playwriting by Jeffrey Hatcher

• Dramatic Writers Companion by Will Dunne

• Backwards and Forwards - A Technical Manual for Reading Plays by David Ball

• Poetics by Aristotle

• The Hidden Plot by Edward Bond

• Theatre of the Oppressed by Augusto Boal

• Brecht on Theatre by Bertolt Brecht

• The Hero with a Thousand Faces by Joseph Campbell

• How to Write Like Chekhov by Anton Chekhov

• Lazzi by Mel Gordon

• On Dramatic Method by Harley Granville-Barker

• Obedience, Struggle & Revolt by David Hare

• Three Uses of the Knife by David Mamet

• Theatre by David Mamet (geared toward actors & directors)

• The Theatre Essays of Arthur Miller by Arthur Miller

• 100 Essays I Don't Have Time to Write by Sarah Ruhl

• The Ground on Which I Stand by August Wilson

• The Crafty Art of Playmaking by Alan Ayckbourn

• The Playwrights Guidebook by Stuart Spencer

• Playwriting with a Purpose by Jacqueline Goldfinger (and her reading list of plays to look at for different topics/skills)

• Playwriting: The Merciless Craft by Carols Wolf

• Letters to a Young Playwright: Practical and Impractical Advice on the Art of Playwriting by Adam Szymkowicz

• Playwriting Seminars 2.0 by Richard Toscan

• How to Write a Play by Raymond Hull