Start with high-confidence stretching books, then narrow by subgenre or adjacent topics.
Yogilates(r)
Jonathan Urla
The Egoscue Method of Health Through Motion
Pete Egoscue
Aging Backwards: Updated and Revised Edition
Miranda Esmonde-White
Stretch and Strengthen
Judith B. Alter, Judy Alter
Pain Free
Pete Egoscue, John Lynch
Better Stretching
Joe Yoon
Chair Pilates and Yoga
Harri Angell
Thriving Beyond Fifty
Will Harlow MSc, MCSP, Cert.MA
End Back Pain Forever
Norman J. Marcus
The Modern Art and Science of Mobility
Aurelien Broussal-Derval, Stephane Ganneau
Stretching Anatomy
Arnold G. Nelson, Jouko Kokkonen
Core Awareness, Revised Edition
Liz Koch
Resistance Band Workbook
Karl Knopf
Becoming a Supple Leopard 2nd Edition
Kelly Starrett, Glen Cordoza
The Strength Training Bible for Seniors
Karl Knopf, Dr. Karl Knopf
The Bodyweight Blueprint
Brad Kolowich Jr., Cody Rhodes
Complete Guide to Foam Rolling
Kyle Stull