Leszek Gasinski, Nikolaos S. Papageorgiou. Nontrivial solutions for Neumann problems with an indefinite linear part. Applied Mathematics and Computation, 217(6):2666-2675, 2010. [doi]
@article{GasinskiP10,
title = {Nontrivial solutions for Neumann problems with an indefinite linear part},
author = {Leszek Gasinski and Nikolaos S. Papageorgiou},
year = {2010},
doi = {10.1016/j.amc.2010.08.004},
url = {http://dx.doi.org/10.1016/j.amc.2010.08.004},
researchr = {https://researchr.org/publication/GasinskiP10},
cites = {0},
citedby = {0},
journal = {Applied Mathematics and Computation},
volume = {217},
number = {6},
pages = {2666-2675},
}