United States. Army. Corps of Topographical Engineers. "South Mountain showing the positions of the forces of the United States and the enemy during the battle fought by the Army of the Potomac under the command of Major General G. B. McClellan, Sept. 14th 1862." Map. S.l: s.n., 1872. Norman B. Leventhal Map & Education Center, https://collections.leventhalmap.org/search/commonwealth:9s161c23k (accessed April 19, 2024).