MLA

Baldwin, James, 1924-1987. Correspondence. Box 1, folder 1-2. 1955-1990, undated. https://collections.library.yale.edu/catalog/33107170.

APA, 6th edition

Baldwin, James, 1924-1987. (["Box 1, folder 1-2"])(1955-1990, undated)[Correspondence]. https://collections.library.yale.edu/catalog/33107170.