Letter from [Person] to [Person], [date]. Box [number], folder [number]. John Cage Correspondence Addenda, Northwestern University Music Library.
Letter from [Person] to [Person], [date]. Box [number], folder [number]. John Cage Correspondence Addenda, Northwestern University Music Library. https://findingaids.library.northwestern.edu/repositories/3/resources/1164 Accessed January 26, 2021.
