@article{GDZPPN00241502X,
title = {Finiteness of the Lower Spectrum of Schr\"odinger Operators.},
journal = {Mathematische Zeitschrift},
volume = {136},
year = {1974},
pages = {29-40},
zbl = {0305.35076},
url = {http://dml.mathdoc.fr/item/GDZPPN00241502X}
}
Piepenbrink, John. Finiteness of the Lower Spectrum of Schrödinger Operators.. Mathematische Zeitschrift, Tome 136 (1974) pp. 29-40. http://gdmltest.u-ga.fr/item/GDZPPN00241502X/