MLA

Jordan, Viola Baxter, 1887-1973. The American Magazine. Box 1, folder 1. n.d.. https://collections.library.yale.edu/catalog/2036295.

APA, 6th edition

Jordan, Viola Baxter, 1887-1973. (["Box 1, folder 1"])(n.d.)[The American Magazine]. https://collections.library.yale.edu/catalog/2036295.