MLA

Pomeroy, S. C. (Samuel Clarke), 1816-1891. Isthmian Pacific Railway Company (mainly correspondence from General S. C. Boynton). Box 1, folder 10. 1890-1895. https://collections.library.yale.edu/catalog/32539894.

APA, 6th edition

Pomeroy, S. C. (Samuel Clarke), 1816-1891. (["Box 1, folder 10"])(1890-1895)[Isthmian Pacific Railway Company (mainly correspondence from General S. C. Boynton)]. https://collections.library.yale.edu/catalog/32539894.