@article{article9963d34a,
title   = {Semilinear elliptic problems near resonance with a nonprincipal eigenvalue},
author = {Paiva, Francisco Odair de and Massa, Eugenio Tommaso},
year = {2008},
doi = {10.1016/j.jmaa.2007.12.053},
journal   = {Journal of Mathematical Analysis and Applications}
}