MLA

McClellan, George Brinton, 1826-1885. Battle of Cerro Gordo, April 17th & 18th 1847 / from surveys made by Major Turnbull & Capt. McClellan, Topl. Engs. ; drawn by Capt. McClellan.. BRBL_00649. 1847?]. https://collections.library.yale.edu/catalog/15822345.

APA, 6th edition

McClellan, George Brinton, 1826-1885. (["BRBL_00649"])(1847?])[Battle of Cerro Gordo, April 17th & 18th 1847 / from surveys made by Major Turnbull & Capt. McClellan, Topl. Engs. ; drawn by Capt. McClellan.]. https://collections.library.yale.edu/catalog/15822345.