ALS to "Sir"
MLA
Norton, Caroline Sheridan, 1808-1877. ALS to "Sir". Box 2, folder 90. 1840 Jun 11. https://collections.library.yale.edu/catalog/16495570.
APA, 6th edition
Norton, Caroline Sheridan, 1808-1877. (["Box 2, folder 90"])(1840 Jun 11)[ALS to "Sir"]. https://collections.library.yale.edu/catalog/16495570.