MLA

Kilpatrick, Jack Frederick (1915-1967). Recto: Journal entry or personal note; Verso: Practice writing of numbers 1-9. Box 5, folder 366. undated. https://collections.library.yale.edu/catalog/15492346.

APA, 6th edition

Kilpatrick, Jack Frederick (1915-1967). (["Box 5, folder 366"])(undated)[Recto: Journal entry or personal note; Verso: Practice writing of numbers 1-9]. https://collections.library.yale.edu/catalog/15492346.