[Letter : 1974 December 20, Georgia O'Keeffe to Edith Asbury]
MLA
O'Keeffe, Georgia, 1887-1986. [Letter : 1974 December 20, Georgia O'Keeffe to Edith Asbury]. Box 1 | Folder 4. 1974 December 20. https://collections.library.yale.edu/catalog/10575627.
APA, 6th edition
O'Keeffe, Georgia, 1887-1986. (["Box 1 | Folder 4"])(1974 December 20)[[Letter : 1974 December 20, Georgia O'Keeffe to Edith Asbury]]. https://collections.library.yale.edu/catalog/10575627.