@article{PORMA_1994__51_4_47276,
     author = {To Fu Ma},
     title = {A note on the existence of two nontrivial solutions of a resonance problem.},
     journal = {Portugaliae mathematica},
     pages = {517--523},
     publisher = {mathdoc},
     volume = {51},
     number = {4},
     year = {1994},
     zbl = {0824.35038},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1994__51_4_47276/}
}