MLA

Buber, Martin, 1878-1965. [Typescript letter signed] 1961 December 17, Jerusalem [to] Judith Malina and Julian Beck. Box 179. 1961. https://collections.library.yale.edu/catalog/2053989.

APA, 6th edition

Buber, Martin, 1878-1965. (["Box 179"])(1961)[[Typescript letter signed] 1961 December 17, Jerusalem [to] Judith Malina and Julian Beck]. https://collections.library.yale.edu/catalog/2053989.