MLA

Jeleński, Konstanty A. (Konstanty Aleksander), 1922-1987. "Eastern Europe," typescript carbon. Box 14, folder 339. undated. https://collections.library.yale.edu/catalog/16612904.

APA, 6th edition

Jeleński, Konstanty A. (Konstanty Aleksander), 1922-1987. (["Box 14, folder 339"])(undated)["Eastern Europe," typescript carbon]. https://collections.library.yale.edu/catalog/16612904.