MLA

Serge, Victor, 1890-1947. Mundo. Box 1, folder 57. 1944-45. https://collections.library.yale.edu/catalog/17455285.

APA, 6th edition

Serge, Victor, 1890-1947. (["Box 1, folder 57"])(1944-45)[Mundo]. https://collections.library.yale.edu/catalog/17455285.