MLA

Gabo, Naum, 1890-1977. Sandberg, Willelm. Box 24. 1939-1980. https://collections.library.yale.edu/catalog/2055183.

APA, 6th edition

Gabo, Naum, 1890-1977. (["Box 24"])(1939-1980)[Sandberg, Willelm]. https://collections.library.yale.edu/catalog/2055183.