@article{PORMA_1993__50_3_115687,
     author = {Amaral, Lu{\'\i}s},
     title = {Nonresonance conditions at the two first eigenvalues for semilinear equations},
     journal = {Portugaliae mathematica},
     pages = {255--262},
     publisher = {mathdoc},
     volume = {50},
     number = {3},
     year = {1993},
     mrnumber = {1244505},
     zbl = {0816.35029},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1993__50_3_115687/}
}