Cite

[Postcard: 1939 January 25, Hampstead, Piet Mondrian to Mr. Carel Mondriaan, Breda, Holland]

MLA

Mondrian, Piet, 1872-1944, Photochrom Co. . [Postcard: 1939 January 25, Hampstead, Piet Mondrian to Mr. Carel Mondriaan, Breda, Holland]. Box 1 | Folder 1. 1939 January 25. https://collections.library.yale.edu/catalog/10061362.

APA, 6th edition

Mondrian, Piet, 1872-1944, & Photochrom Co. . (["Box 1 | Folder 1"])(1939 January 25)[[Postcard: 1939 January 25, Hampstead, Piet Mondrian to Mr. Carel Mondriaan, Breda, Holland]]. https://collections.library.yale.edu/catalog/10061362.