Amherst, Jeffery Amherst, Baron, and Royal United Services Institute for Defence and Security Studies. "[Map showing Fort Pitt, Fort Duquesne and Fort Mercer]." Map. Place of production not identified: Producer not identified, [ca. 1761]. Norman B. Leventhal Map & Education Center, https://collections.leventhalmap.org/search/commonwealth:hx11z221m (accessed April 23, 2024).