@article{ASNSP_1978_4_5_1_15_0,
     author = {Ambrosetti, Antonio and Mancini, Giovanni},
     title = {Theorems of existence and multiplicity for nonlinear elliptic problems with noninvertible linear part},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {15--28},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 5},
     number = {1},
     year = {1978},
     mrnumber = {487001},
     zbl = {0375.35024},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1978_4_5_1_15_0/}
}