MLA

Weber, Carl Maria von, 1786-1826. Der Freischütz : romantische Oper in 3 Aufzügen. Box 144 | Folder 765. [1820s?]. https://collections.library.yale.edu/catalog/10000214.

APA, 6th edition

Weber, Carl Maria von, 1786-1826. (["Box 144 | Folder 765"])([1820s?])[Der Freischütz : romantische Oper in 3 Aufzügen]. https://collections.library.yale.edu/catalog/10000214.