MLA

Marinetti, F. T., 1876-1944. [1910 Aug 24] Postcard; [1913 Jul 25] Postcard; in an envelope, with the following four postcards, labelled "Cartoline Apollinaire" and the dates, in the hand of BCM; 1913 Dec 20 Postcard; [1914 May 18] Postcard; [1917 Oct 28] Postcard; [1918 Aug 12] Postcard. Box 7, folder 97. 1898-1970. https://collections.library.yale.edu/catalog/2017250.

APA, 6th edition

Marinetti, F. T., 1876-1944. (["Box 7, folder 97"])(1898-1970)[[1910 Aug 24] Postcard; [1913 Jul 25] Postcard; in an envelope, with the following four postcards, labelled "Cartoline Apollinaire" and the dates, in the hand of BCM; 1913 Dec 20 Postcard; [1914 May 18] Postcard; [1917 Oct 28] Postcard; [1918 Aug 12] Postcard]. https://collections.library.yale.edu/catalog/2017250.