MLA

Fitzgerald, Robert, 1910-1985. "Sophocles... Virgil Aen I & II". Box 98, folder 3432. n.d.. https://collections.library.yale.edu/catalog/17427395.

APA, 6th edition

Fitzgerald, Robert, 1910-1985. (["Box 98, folder 3432"])(n.d.)["Sophocles... Virgil Aen I & II"]. https://collections.library.yale.edu/catalog/17427395.