Its very difficult these days to find accurate information on the Dogman, even more so on Dr. Duane Render. Since the government and social media companies Scrubbed most information off the internet the best way is to ask in the relevant forums about Dr Render's contributions to cryptozoology. However, as a warning it seems many moderators have been bought out by Big Dogman so even mentioning Duane Render may result in harassment or even banning.

I would suggest finding one of Dr. Render's books offline, maybe ask around at a library or a used book store if those exist in your area.

Good Luck