comments:
subgeniusbuttpirate posted on r/analonlylifestyle1w
There really isn't a lot of research on anal sex in general. Even proctologists seem to avoid doing any studies on the subject. There's a fairly recent book on butt sex, if you want to give it a read: https://www.amazon.com/Butt-Seriously-Definitive-Pleasure-Everything/dp/1538757478/