@article{CMH_1946__19_138907,
     author = {B\'ela de S de Nagy},
     title = {Perturbations des transformations autoadjointes dans l'espace de {Hilbert.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {347--366},
     publisher = {mathdoc},
     volume = {19},
     year = {1946},
     zbl = {0035.20001},
     url = {http://geodesic.mathdoc.fr/item/CMH_1946__19_138907/}
}