Three-Component Spinors Asher Peres Indiana University Mathematics Journal 1962 text pdf 10.1512/iumj.1962.11.11004 10.1512/iumj.1962.11.11004 en Indiana Univ. Math. J. 11 (1962) 61 - 79 state-of-the-art mathematics http://iumj.org/access/