MLA

Gombrowicz, Witold, 1904-1969. Wittlin, Józef. Box 11, folder 429-430. 19[51]-62. https://collections.library.yale.edu/catalog/2007781.

APA, 6th edition

Gombrowicz, Witold, 1904-1969. (["Box 11, folder 429-430"])(19[51]-62)[Wittlin, Józef]. https://collections.library.yale.edu/catalog/2007781.