The de Rham Theorem for Function Spaces F. Flaherty Indiana University Mathematics Journal 1970 text pdf 10.1512/iumj.1970.19.19030 10.1512/iumj.1970.19.19030 en Indiana Univ. Math. J. 19 (1970) 317 - 320 state-of-the-art mathematics http://iumj.org/access/