Papurau Cassie Simon yn ymwneud â Chôr Plant Cwmdwr neu â phlant a hyfforddwyd ganddi,yn cynnwys rhaglenni cyngherddau, 1932-1986; posteri, 1947-1958; torion papur newydd, 1933-1974; beirniadaethau eisteddfodau a thystysgrifau, 1947-1956; a gohebiaeth a phapurau cyffredinol, 1957-1989 = Papers of Cassie Simon relating to Côr Plant Cwmdwr or to children instructed by her, including concert programmes, 1932-1986; posters, 1947-1958; newspaper cuttings, 1933-1974; eisteddfod adjudications and certificates, 1947-1956; and general correspondence and papers, 1957-1989.