MLA

Streeter, Thomas W. (Thomas Winthrop), 1883-1965. Signed memorandum, San Felipe de Austin. Box 1, folder 15. 1829 Feb 18. https://collections.library.yale.edu/catalog/10906664.

APA, 6th edition

Streeter, Thomas W. (Thomas Winthrop), 1883-1965. (["Box 1, folder 15"])(1829 Feb 18)[Signed memorandum, San Felipe de Austin]. https://collections.library.yale.edu/catalog/10906664.