MLA

Bélugou, Léon, 1865-1934. Léon Bélugou correspondence, 1908-1934. Box 1. https://collections.library.yale.edu/catalog/16044039.

APA, 6th edition

Bélugou, Léon, 1865-1934. (["Box 1"])[Léon Bélugou correspondence, 1908-1934]. https://collections.library.yale.edu/catalog/16044039.