Solutions of a Riccati Matrix Differential Equation as Functions of Initial Values William Reid Indiana University Mathematics Journal 1959 text pdf 10.1512/iumj.1959.8.58016 10.1512/iumj.1959.8.58016 en Indiana Univ. Math. J. 8 (1959) 221 - 230 state-of-the-art mathematics http://iumj.org/access/