The Quarterly Journal of MathematicsON THE NATURE OF THE SPECTRUM IN PROBLEMS OF RELATIVISTIC QUANTUM MECHANICSEdward Charles TitchmarshPublished Jan 1, 1961• 35 citationsPublisherAbstractE. C. TITCHMARSH; ON THE NATURE OF THE SPECTRUM IN PROBLEMS OF RELATIVISTIC QUANTUM MECHANICS, The Quarterly Journal of Mathematics, Volume 12, Issue 1, 1 JanuaDOI10.1093/qmath/12.1.227