MLA

Du Bois, W. E. B. (William Edward Burghardt), 1868-1963. Later draft, typescript, corrected, incomplete. Box 1, folder 27-28. n.d.. https://collections.library.yale.edu/catalog/2040342.

APA, 6th edition

Du Bois, W. E. B. (William Edward Burghardt), 1868-1963. (["Box 1, folder 27-28"])(n.d.)[Later draft, typescript, corrected, incomplete]. https://collections.library.yale.edu/catalog/2040342.