@article{GDZPPN001183745,
title = {Small Potential Corrections for the Discrete Eigenvalues of the Sturm-Liouville Problem.},
journal = {Numerische Mathematik},
volume = {58},
year = {1990},
pages = {51-62},
zbl = {0698.65051},
url = {http://dml.mathdoc.fr/item/GDZPPN001183745}
}
Marti, Jürg T. Small Potential Corrections for the Discrete Eigenvalues of the Sturm-Liouville Problem.. Numerische Mathematik, Tome 58 (1990) pp. 51-62. http://gdmltest.u-ga.fr/item/GDZPPN001183745/