Date: 8 Tamuz 5563
From: Rabbi Moshe Sofer
To: Rabbi Moshe Segal
The responsum discusses whether a yavam's relations with his yevamah without witnesses constitutes a valid acquisition, referencing a query from the Shilti Giborim and a difficulty from Tractate Sotah.
Source: Shu"t Chasam Sofer CM §201