MLA

Miłosz, Czesław, 1911-2004. Letter pad. Box 130, folder 2081. 1990s. https://collections.library.yale.edu/catalog/10050423.

APA, 6th edition

Miłosz, Czesław, 1911-2004. (["Box 130, folder 2081"])(1990s)[Letter pad]. https://collections.library.yale.edu/catalog/10050423.