MLA

Scull, William, active 1765, cartographer. A map of Pennsylvania exhibiting not only the improved parts of that Province, but also its extensive frontiers: Laid down from actual surveys, and chiefly from the late map of W. Scull published in 1770; and humbly inscribed to the Honorable Thomas Penn . BRBL_00497. 10 June 1775.. https://collections.library.yale.edu/catalog/15790122.

APA, 6th edition

Scull, William, active 1765, cartographer. (["BRBL_00497"])(10 June 1775.)[A map of Pennsylvania exhibiting not only the improved parts of that Province, but also its extensive frontiers: Laid down from actual surveys, and chiefly from the late map of W. Scull published in 1770; and humbly inscribed to the Honorable Thomas Penn ]. https://collections.library.yale.edu/catalog/15790122.