00290nam a2200121Ia 4500082002000000100002200020245002900042260003400071300001400105490003900119500000500158700000500163  a515.72bF228.SA  aFaris, William G.  aSelf-adjoint operatorsb  aBerlinbSpringer-Verlagc1975  avi, 115p.  aLecture notes in Mathematicsv 433  a  a