MLA

Hulme, Kathryn, 1900-1981. Gurdjieff "lecture notes". Box 54, folder 758-61. 1922-39, n.d.. https://collections.library.yale.edu/catalog/10591959.

APA, 6th edition

Hulme, Kathryn, 1900-1981. (["Box 54, folder 758-61"])(1922-39, n.d.)[Gurdjieff "lecture notes"]. https://collections.library.yale.edu/catalog/10591959.