Poised and Non-Poised Hermite-Birkhoff Interpolation Samuel KarlinJohn Karon Indiana University Mathematics Journal 1972 text pdf 10.1512/iumj.1972.21.21090 10.1512/iumj.1972.21.21090 en Indiana Univ. Math. J. 21 (1972) 1131 - 1170 state-of-the-art mathematics http://iumj.org/access/