@article{MAN_1979__243_182802,
     author = {Helmut Reckziegel},
     title = {On the {Eigenvalues} of the {Shape} {Operator} of an {Isometric} {Immersion} into a {Space} of {Constant} {Curvature.}},
     journal = {Mathematische Annalen},
     pages = {71--82},
     publisher = {mathdoc},
     volume = {243},
     year = {1979},
     zbl = {0393.53037},
     url = {http://geodesic.mathdoc.fr/item/MAN_1979__243_182802/}
}