@article{CMUC_1995_36_4_a5,
     author = {O'Regan, Donal},
     title = {Differential equations at resonance},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {673--694},
     year = {1995},
     volume = {36},
     number = {4},
     mrnumber = {1378689},
     zbl = {0843.34029},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1995_36_4_a5/}
}