@article{GDZPPN002484137,
title = {Singular Sturm-Liouville Problems with Nonnegative and Indefinite Weights.},
journal = {Monatshefte f\"ur Mathematik},
volume = {98},
year = {1984},
pages = {177-190},
zbl = {0535.34019},
url = {http://dml.mathdoc.fr/item/GDZPPN002484137}
}
Kaper, H.G.; Kwong, M.K.; Zettl, A. Singular Sturm-Liouville Problems with Nonnegative and Indefinite Weights.. Monatshefte für Mathematik, Tome 98 (1984) pp. 177-190. http://gdmltest.u-ga.fr/item/GDZPPN002484137/