MLA

Morpurgo, Nelson, 1899-1978. "Un'avventura 'by night'". Box 1, folder 9. n.d.. https://collections.library.yale.edu/catalog/2109177.

APA, 6th edition

Morpurgo, Nelson, 1899-1978. (["Box 1, folder 9"])(n.d.)["Un'avventura 'by night'"]. https://collections.library.yale.edu/catalog/2109177.