Petchpanomrung Kiatmookao is thought by many to be the pound for pound hardest kicker today. His roundhouse is absolutely crushing, and I was lucky enough to visit him at his gym and ask him the secrets behind it. As well as one of the coolest knockouts ever captured on film.
Glory 86 Info: https://www.glorykickboxing.com/events/glory-86:312b8317-029a-4647-a6e6-c0f3f08927e3
Muay Thai Academy Info: https://www.muaythaiacademy.ca
TMMA Books: https://www.modernmartialartist.com/technique-books-by-tmma-david-christian/