Cite

A map of Messrs. Gorham and Phelp's Purchase; now the County of Ontario in the State of New York From actual survey by A. Porter Engraved by A. Doolitle, New Haven.

MLA

A Map of Messrs. Gorham and Phelp's Purchase; Now the County of Ontario in the State of New York From Actual Survey by A. Porter Engraved by A. Doolitle, New Haven. 0AD. https://collections.library.yale.edu/catalog/15762454.

APA, 6th edition

A map of Messrs. Gorham and Phelp's Purchase; now the County of Ontario in the State of New York From actual survey by A. Porter Engraved by A. Doolitle, New Haven. (0 C.E.). [Maps]. https://collections.library.yale.edu/catalog/15762454.