cx b22 3 45 128705191 http://www.idref.fr/128705191 20081029 20200921205524.000 335222228 751052352 Tb5 http://viaf.org/viaf/268250840 VIAF VIAF 20200401 20081029afrey50 ba0 eng US 19600724 19600819 0 1 0 y AFNOR ba0yba0y 0 Summer Seminar on Applied Mathematics 1960 Boulder (Colo.) FR Abes 20200921 AFNOR Perturbation of spectra in Hilbert space / by Kurt O. Friedrichs, 1965 Summer Seminar on Applied Mathematics (1960 ; Boulder (Colo.))