@article{RCM_1976__10_181644,
     author = {Klaus Kalb},
     title = {Teorema y funciones de multiplicidad espectral},
     journal = {Revista colombiana de matematicas},
     pages = {1--38},
     publisher = {mathdoc},
     volume = {10},
     year = {1976},
     url = {http://geodesic.mathdoc.fr/item/RCM_1976__10_181644/}
}