From: Rabbi Moshe Sofer
To: Rabbi Naftali
The question is whether a middle village in a triangulated formation must be within 141⅓ amos of both outer villages to join them for techum Shabbos. The Chasam Sofer firmly rules that the middle village must be close to both outer villages, rejecting all arguments for one-sided application of the ro'in principle.
Source: Shu"t Chasam Sofer OC §94