Postcard from ethnomusiologist Sidney Robertson Cowell to Frances Schillinger, asking about the Rhythmicon [the first electronic rhythm machine built by Russian inventor Louis Theremin]: "could a composer afford to buy it? ...

Letter from ethnomusicologist Sidney Robertson Cowell to Frances Schillinger, letting her know that "Henry has been ill…and it is unfortunately impossible for him to undertake to write anything - he is sorry."

Letter from ethnomusicologist Sidney Robertson Cowell to Frances Schillinger, presumably thanking her for her condolences on the death of composer Henry Cowell.