@article{01779096, title = {Boundedness and monotonicity of principal eigenvalues for boundary value problems with indefinite weight functions.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {30}, year = {2002}, pages = {25-29}, doi = {10.1155/S0161171202007780}, zbl = {1005.35033}, language = {en}, url = {http://dml.mathdoc.fr/item/01779096} }
Afrouzi, G.A. Boundedness and monotonicity of principal eigenvalues for boundary value problems with indefinite weight functions.. International Journal of Mathematics and Mathematical Sciences, Tome 30 (2002) pp. 25-29. doi : 10.1155/S0161171202007780. http://gdmltest.u-ga.fr/item/01779096/