Let’s have a look at what hatha yoga was to the yogis who invented it. It is quite different from that which is taught in modern studios.
Hatha Yoga Poses: 11 Easy Poses for Beginners & Its Benefits - Fitsri Yoga
PDF) Haṭha Yoga - entry in Vol. 3 of the Brill Encyclopedia of Hinduism
The Truth of Yoga
A Brief History of Hatha Yoga - Yoga Teacher Training in Rishikesh – The Bodhi Yoga India
Yoga is Not Demonic - by David Armstrong
Sanskrit Archives - Yoga Paper
YS 206 The Amṛtasiddhi: Haṭha Yoga's Source Text
Summary Of The Hatha Yoga Pradipika That Every Yogi Can Benefit From Knowing
Hatha Yoga Definition & What To Expect In A Hatha Yoga Class
Yoga: Methods, types, philosophy, and risks