MLA

Douglas, Norman, 1868-1952. General. Box 34, folder 566-67. 1892, 1898, undated. https://collections.library.yale.edu/catalog/32261754.

APA, 6th edition

Douglas, Norman, 1868-1952. (["Box 34, folder 566-67"])(1892, 1898, undated)[General]. https://collections.library.yale.edu/catalog/32261754.