MLA

Simpson, Randolph Linsly, 1927-1992. W.H. Horne Co., El Paso, TX "A little game of chance:" four soldiers play cards on a blanket outdoors. Photographic postcard. Box 25, folder 1038. circa 1918. https://collections.library.yale.edu/catalog/16172744.

APA, 6th edition

Simpson, Randolph Linsly, 1927-1992. (["Box 25, folder 1038"])(circa 1918)[W.H. Horne Co., El Paso, TX "A little game of chance:" four soldiers play cards on a blanket outdoors. Photographic postcard]. https://collections.library.yale.edu/catalog/16172744.