MLA

Marinetti, F. T., 1876-1944. Depero. Letter sent to Benedetta for Christmas 1930, announcing the sending of trees from Rovereto. Rovereto, 22 dic 1930. [6845-1]. box 86, slide 65. 1930. https://collections.library.yale.edu/catalog/10659510.

APA, 6th edition

Marinetti, F. T., 1876-1944. (["box 86, slide 65"])(1930)[Depero. Letter sent to Benedetta for Christmas 1930, announcing the sending of trees from Rovereto. Rovereto, 22 dic 1930. [6845-1]]. https://collections.library.yale.edu/catalog/10659510.