@article{MAN_1970__184_161923,
     author = {D.C. LAY},
     title = {Spectral {Analysis} {Using} {Ascent,} {Descent,} {Nullity} and {Defect.}},
     journal = {Mathematische Annalen},
     pages = {197--214},
     publisher = {mathdoc},
     volume = {184},
     year = {1970},
     zbl = {0177.17102},
     url = {http://geodesic.mathdoc.fr/item/MAN_1970__184_161923/}
}