Durell, Philip, -1766,  George, III, King of Great Britain,  George, IV, King of Great Britain,  and Bastide, John Henry, approximately 1700-1770.  "Plan of the HARBOUR and FORTIFICATIONS OF LOUISBOURG."  Map.  1745.  Norman B. Leventhal Map & Education Center,  https://collections.leventhalmap.org/search/commonwealth:hx11z5438 (accessed June 27, 2019).