MLA

Hammond, C. S., and Company. Maps of Allied Assaults on Fortress Europe; Europe, France, Italy, Netherlands and Belgium. C.S. Hammond & Co., 0AD. https://collections.library.yale.edu/catalog/15258802.

APA, 6th edition

Hammond, C. S., & C. (0 C.E.). Maps of allied assaults on fortress Europe; Europe, France, Italy, Netherlands and Belgium. [Maps]. C.S. Hammond & Co., https://collections.library.yale.edu/catalog/15258802.