MLA

Geldzahler, Henry, 1935-1994. Francis Bacon: approximately 60 page file including typed drafts and correspondence regarding essay for 1974 catalogue, Metropolitan Museum of Art. Box 5, folder 187. circa 1974. https://collections.library.yale.edu/catalog/32589204.

APA, 6th edition

Geldzahler, Henry, 1935-1994. (["Box 5, folder 187"])(circa 1974)[Francis Bacon: approximately 60 page file including typed drafts and correspondence regarding essay for 1974 catalogue, Metropolitan Museum of Art]. https://collections.library.yale.edu/catalog/32589204.