MLA

Sanborn-Perris Map Co., issuing body. Unionville, Hartford Co., Conn. 1892. https://collections.library.yale.edu/catalog/11675405.

APA, 6th edition

Sanborn-Perris Map Co., issuing body. (1892). Unionville, Hartford Co., Conn. [Atlases--Connecticut--Unionville--1892, Cadastral maps--Connecticut--Unionville--1892, Fire insurance maps--Connecticut--Unionville--1892]. https://collections.library.yale.edu/catalog/11675405.