A Factorization of Positive Hermitian Matrices E. AkutowiczN. Wiener Indiana University Mathematics Journal 1959 text pdf 10.1512/iumj.1959.8.58007 10.1512/iumj.1959.8.58007 en Indiana Univ. Math. J. 8 (1959) 111 - 120 state-of-the-art mathematics http://iumj.org/access/