Cite

[Letter: 1938 October 28, Piet Mondrian to Carel and Mary Mondriaan]

MLA

Mondrian, Piet, 1872-1944. [Letter: 1938 October 28, Piet Mondrian to Carel and Mary Mondriaan]. Box 1 | Folder 1. 1938 October 28. https://collections.library.yale.edu/catalog/10081361.

APA, 6th edition

Mondrian, Piet, 1872-1944. (["Box 1 | Folder 1"])(1938 October 28)[[Letter: 1938 October 28, Piet Mondrian to Carel and Mary Mondriaan]]. https://collections.library.yale.edu/catalog/10081361.