Hammond's large scale war map of the Western Front.
MLA
Hammond, C. S., and Company. Hammond's Large Scale War Map of the Western Front. C.S. Hammond, 1917. https://collections.library.yale.edu/catalog/15237941.
APA, 6th edition
Hammond, C. S., & C. (1917). Hammond's large scale war map of the Western Front. [Maps]. C.S. Hammond, https://collections.library.yale.edu/catalog/15237941.