Cite

The Upper Mississippi system, and the Missouri system as far as the Mandans.

MLA

Clark, William, 1770-1838. The Upper Mississippi system, and the Missouri system as far as the Mandans.. Box 1, folder 2. circa 1803-1810. https://collections.library.yale.edu/catalog/2002442.

APA, 6th edition

Clark, William, 1770-1838. (["Box 1, folder 2"])(circa 1803-1810)[The Upper Mississippi system, and the Missouri system as far as the Mandans.]. https://collections.library.yale.edu/catalog/2002442.