MLA

Tchelitchew, Pavel, 1898-1957. Crevel, René. Box 1, folder 29. 1926-1930, undated. https://collections.library.yale.edu/catalog/17204708.

APA, 6th edition

Tchelitchew, Pavel, 1898-1957. (["Box 1, folder 29"])(1926-1930, undated)[Crevel, René]. https://collections.library.yale.edu/catalog/17204708.