MLA

Lord, James, 1922-2009. Acton, Harold. Box 1, folder 2-4. 1951-1985, undated. https://collections.library.yale.edu/catalog/16622477.

APA, 6th edition

Lord, James, 1922-2009. (["Box 1, folder 2-4"])(1951-1985, undated)[Acton, Harold]. https://collections.library.yale.edu/catalog/16622477.