Photographic portrait of J. Willard Gibbs by Pach Bros., New York.
MLA
Gibbs, J. Willard (Josiah Willard), 1839-1903. Photographic portrait of J. Willard Gibbs by Pach Bros., New York.. Box 18, folder 287. undated. https://collections.library.yale.edu/catalog/2020783.
APA, 6th edition
Gibbs, J. Willard (Josiah Willard), 1839-1903. (["Box 18, folder 287"])(undated)[Photographic portrait of J. Willard Gibbs by Pach Bros., New York.]. https://collections.library.yale.edu/catalog/2020783.