Cite

"Preface to a Book of Poems"

MLA

Williams, William Carlos, 1883-1963. "Preface to a Book of Poems". Box 44, folder 1099. undated. https://collections.library.yale.edu/catalog/17433314.

APA, 6th edition

Williams, William Carlos, 1883-1963. (["Box 44, folder 1099"])(undated)["Preface to a Book of Poems"]. https://collections.library.yale.edu/catalog/17433314.