Mumm, Walter, account of a balloon race in Stuttgart, Germany
MLA
Wilson, Elena, 1906-1979. Mumm, Walter, account of a balloon race in Stuttgart, Germany. Box 30, folder 732. n.d.. https://collections.library.yale.edu/catalog/17197611.
APA, 6th edition
Wilson, Elena, 1906-1979. (["Box 30, folder 732"])(n.d.)[Mumm, Walter, account of a balloon race in Stuttgart, Germany]. https://collections.library.yale.edu/catalog/17197611.