I'd never heard about this before, but apparently one of the Undermountain maps includes the map from B1 In Search...

I'd never heard about this before, but apparently one of the Undermountain maps includes the map from B1 In Search of the Unknown. I just saw it mentioned on twitter, but Dyson Logos blogged about it back in 2011! Per his post it's in the Eastern part of Level 1. Other parts of the maps come from a Tekumel megadungeon that David Sutherland drew back in '70s.

https://www.google.com/amp/s/dysonlogos.blog/2011/02/26/confessions-of-a-grognard-i-undermountain/amp/
https://www.google.com/amp/s/dysonlogos.blog/2011/02/26/confessions-of-a-grognard-i-undermountain/amp/