On the Swirling Flow Problem Philip Hartman Indiana University Mathematics Journal 1972 text pdf 10.1512/iumj.1972.21.21069 10.1512/iumj.1972.21.21069 en Indiana Univ. Math. J. 21 (1972) 849 - 855 state-of-the-art mathematics http://iumj.org/access/