Traubel, [Horace] to [William F.?] Gable
MLA
Whitman, Walt, 1819-1892. Traubel, [Horace] to [William F.?] Gable. Box 2, folder 106. 1908 Apr 30. https://collections.library.yale.edu/catalog/2053740.
APA, 6th edition
Whitman, Walt, 1819-1892. (["Box 2, folder 106"])(1908 Apr 30)[Traubel, [Horace] to [William F.?] Gable]. https://collections.library.yale.edu/catalog/2053740.