MLA

Marsh, Othniel Charles, 1831-1899. Red Cloud Correspondence. Box 52, folder 14. 1875 July 1-6. https://collections.library.yale.edu/catalog/32510123.

APA, 6th edition

Marsh, Othniel Charles, 1831-1899. (["Box 52, folder 14"])(1875 July 1-6)[Red Cloud Correspondence]. https://collections.library.yale.edu/catalog/32510123.