Commutators and Scattering Theory II. A Class of One Body Problems Richard Lavine Indiana University Mathematics Journal 1972 text pdf 10.1512/iumj.1972.21.21050 10.1512/iumj.1972.21.21050 en Indiana Univ. Math. J. 21 (1972) 643 - 656 state-of-the-art mathematics http://iumj.org/access/