MLA

Pound, Ezra, 1885-1972. Gaudier-Brzeska, Henri. Box 7, folder 163. 1914-15, n.d.. https://collections.library.yale.edu/catalog/17180217.

APA, 6th edition

Pound, Ezra, 1885-1972. (["Box 7, folder 163"])(1914-15, n.d.)[Gaudier-Brzeska, Henri]. https://collections.library.yale.edu/catalog/17180217.