Practical Shooting: Beyond Fundamentals, Brian Enos
, he has a number of excellent books available. I would consider him my go-to author for pistolcraft. Refinement and Repetition (Steve Anderson) is an outstanding workbook to guide and track your development.
Surgical Speed Shooting: How To Achieve High-Speed Marksmanship In A Gunfight, Andy Stafford
T.A.P.S. Tactical Application of Practical Shooting: Recognize the void in your tactical training, Patrick McNamara
Tactical Pistol Shooting: Your Guide to Tactics & Techniques that Work, Eric Lawrence
The Gun Digest Book of Combat Handgunnery, Massad Ayoob
The Gun Digest Book Of Concealed Carry, Massad Ayoob
Stressfire, Vol. 1 (Gunfighting for Police: Advanced Tactics and Techniques), Massad Ayoob
I can also personally recommend Rob Pincus as an excellent instructor, although there are dozens of them out there. James Yeager, Clint Smith, etc. Pincus posts on here and you can enjoy his videos on Personal Defense Network.
The Magpul stuff is okay, but highly dramatized and not for everybody. Some of the techniques they employ (like shooting over the hood of a car, or using an A-pillar for cover) just don't stand up to real-world muster.
Hope it helps. Go slow, be safe, do it right. Speed comes with time.