The Holonomy Group V. Weyl Space W_4, First Part* Vaiclav Hlavaty Indiana University Mathematics Journal 1961 text pdf 10.1512/iumj.1961.10.10021 10.1512/iumj.1961.10.10021 en Indiana Univ. Math. J. 10 (1961) 317 - 348 state-of-the-art mathematics http://iumj.org/access/