Cohomology of Forms with Values in a Graded Lie Algebra Rene Ruchti Indiana University Mathematics Journal 1975 text pdf 10.1512/iumj.1975.24.24092 10.1512/iumj.1975.24.24092 en Indiana Univ. Math. J. 24 (1975) 1099 - 1117 state-of-the-art mathematics http://iumj.org/access/