@article{GDZPPN002206668,
title = {Boundary problems of the second order with an indefinite weight-function.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {394},
year = {1989},
pages = {1-24},
zbl = {0668.35073},
url = {http://dml.mathdoc.fr/item/GDZPPN002206668}
}
Allegretto, W.; Mingarelli, A.B. Boundary problems of the second order with an indefinite weight-function.. Journal für die reine und angewandte Mathematik, Tome 394 (1989) pp. 1-24. http://gdmltest.u-ga.fr/item/GDZPPN002206668/