MLA

Map, Sanborn, and issuing body Publishing Co. Unionville, Conn. 1884. https://collections.library.yale.edu/catalog/11675404.

APA, 6th edition

Map, S., & Publishing Co., issuing body. (1884). Unionville, Conn. [Atlases--Connecticut--Unionville--1884, Cadastral maps--Connecticut--Unionville--1884, Fire insurance maps--Connecticut--Unionville--1884]. https://collections.library.yale.edu/catalog/11675404.