MLA

Hammond, C. S., and Company. Hammond's Large Scale War Map of the Western Front ; Hammond's Large Scale War Map Italian Front [Cartographic Material]. C.S. Hammond & Co. (Incorporated) Engravers, Printers, Publishers 30 Church Street (Hudson Terminal), 0AD. https://collections.library.yale.edu/catalog/15237994.

APA, 6th edition

Hammond, C. S., & C. (0 C.E.). Hammond's large scale war map of the Western Front ; Hammond's large scale war map Italian Front [cartographic material]. [Maps]. C.S. Hammond & Co. (Incorporated) Engravers, Printers, Publishers 30 Church Street (Hudson Terminal), https://collections.library.yale.edu/catalog/15237994.