MLA

Hughes, Langston, 1902-1967. Selected Poems of Gabriela Mistral, notes. Box 425, folder 9455. 1957-59. https://collections.library.yale.edu/catalog/17426422.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 425, folder 9455"])(1957-59)[Selected Poems of Gabriela Mistral, notes]. https://collections.library.yale.edu/catalog/17426422.