MLA

Adlum, John, 1759-1836. A map exhibiting a general view of the roads and inland navigation of Pennsylvania, and part of the adjacent states : respectfully inscribed to Thomas Mifflin, governor, and the General Assembly of the commonwealth of Pennsylvania / by John Adlum, and John Wallis. [1791]. https://collections.library.yale.edu/catalog/2057167.

APA, 6th edition

Adlum, John, 1759-1836. ([1791])[A map exhibiting a general view of the roads and inland navigation of Pennsylvania, and part of the adjacent states : respectfully inscribed to Thomas Mifflin, governor, and the General Assembly of the commonwealth of Pennsylvania / by John Adlum, and John Wallis]. https://collections.library.yale.edu/catalog/2057167.