MLA

Sayer, Robert, 1725-1794, cartographer. 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. July the 1st, 1787.. https://collections.library.yale.edu/catalog/2046630.

APA, 6th edition

Sayer, Robert, 1725-1794, cartographer. (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/2046630.