MLA

Marsh, Othniel Charles, 1831-1899. Heldreich, T.. Box 16, folder 643. 1871. https://collections.library.yale.edu/catalog/32560331.

APA, 6th edition

Marsh, Othniel Charles, 1831-1899. (["Box 16, folder 643"])(1871)[Heldreich, T.]. https://collections.library.yale.edu/catalog/32560331.