MLA

Phillips, Ulrich Bonnell, 1877-1934. Correspondence, 1850-1879. Box 3, folder 44-71. 1850-1879. https://collections.library.yale.edu/catalog/10021742.

APA, 6th edition

Phillips, Ulrich Bonnell, 1877-1934. (["Box 3, folder 44-71"])(1850-1879)[Correspondence, 1850-1879]. https://collections.library.yale.edu/catalog/10021742.