The Quarterly Journal of MathematicsON THE NATURE OF THE SPECTRUM IN PROBLEMS OF RELATIVISTIC QUANTUM MECHANICS (II)Edward Charles TitchmarshPublished Jan 1, 1962• 4 citationsPublisherAbstractE. C. TITCHMARSH; ON THE NATURE OF THE SPECTRUM IN PROBLEMS OF RELATIVISTIC QUANTUM MECHANICS (II), The Quarterly Journal of Mathematics, Volume 13, Issue 1, 1DOI10.1093/qmath/13.1.181