MLA

Jefferys, Thomas, -1771. A new map of Nova Scotia, and Cape Breton Island : with the adjacent parts of New England and Canada, composed from a great number of actual surveys; and other materials regulated by many new astronomical observations of the longitude as well as latitude. BRBL_00727. 15 June 1775.. https://collections.library.yale.edu/catalog/15830752.

APA, 6th edition

Jefferys, Thomas, -1771. (["BRBL_00727"])(15 June 1775.)[A new map of Nova Scotia, and Cape Breton Island : with the adjacent parts of New England and Canada, composed from a great number of actual surveys; and other materials regulated by many new astronomical observations of the longitude as well as latitude]. https://collections.library.yale.edu/catalog/15830752.