MLA

Malinowski, Bronislaw, 1884-1942. Kunerolwerke, Emanuel Khuner and Son [business correspondence with Paul Khuner]. Box 9, folder 684, reel 6 | reel 6U. 1927-1931. https://collections.library.yale.edu/catalog/32502306.

APA, 6th edition

Malinowski, Bronislaw, 1884-1942. (["Box 9, folder 684, reel 6 | reel 6U"])(1927-1931)[Kunerolwerke, Emanuel Khuner and Son [business correspondence with Paul Khuner]]. https://collections.library.yale.edu/catalog/32502306.