Amherst, Jeffery Amherst, Baron,  and Royal United Services Institute for Defence and Security Studies.  "Plan et Elevation de la Batterie Royalle, dans le port de louisbourg, en l'isle royale."  Map.  1751.  Norman B. Leventhal Map & Education Center,  https://collections.leventhalmap.org/search/commonwealth:hx11z042z (accessed September 25, 2021).