Bilinear Forms in Hilbert Space A. McIntosh Indiana University Mathematics Journal 1970 text pdf 10.1512/iumj.1970.19.19082 10.1512/iumj.1970.19.19082 en Indiana Univ. Math. J. 19 (1970) 1027 - 1045 state-of-the-art mathematics http://iumj.org/access/