MLA

Sayer, Robert, 1725-1794. A map of South America : containing Tierra-Firma, Guayana, New Granada, Amazonia, Brasil, Peru, Paraguay, Chaco, Tucuman, Chili and Patagonia : from Mr. d'Anville with several improvements and additions, and the newest discoveries.. BRBL_00661. July the 1st, 1787.. https://collections.library.yale.edu/catalog/15821003.

APA, 6th edition

Sayer, Robert, 1725-1794. (["BRBL_00661"])(July the 1st, 1787.)[A map of South America : containing Tierra-Firma, Guayana, New Granada, Amazonia, Brasil, Peru, Paraguay, Chaco, Tucuman, Chili and Patagonia : from Mr. d'Anville with several improvements and additions, and the newest discoveries.]. https://collections.library.yale.edu/catalog/15821003.