MLA

Marinetti, F. T., 1876-1944. Cesare Angelini. Manuscript letter to Marinetti inviting him to give a lecture on Futurism in Pavia. Colegio Borromeo, Pavia, 14 nov 1939. [8742-1]. box 110, slide 42. 1939. https://collections.library.yale.edu/catalog/10663091.

APA, 6th edition

Marinetti, F. T., 1876-1944. (["box 110, slide 42"])(1939)[Cesare Angelini. Manuscript letter to Marinetti inviting him to give a lecture on Futurism in Pavia. Colegio Borromeo, Pavia, 14 nov 1939. [8742-1]]. https://collections.library.yale.edu/catalog/10663091.