no. 3

Nonlinear perturbations of linear elliptic and parabolic problems at resonance : existence of multiple solutions
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 5 (1978) no. 3, pp. 527-537. 
@article{ASNSP_1978_4_5_3_527_0,
     author = {Hess, Peter},
     title = {Nonlinear perturbations of linear elliptic and parabolic problems at resonance : existence of multiple solutions},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {527--537},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 5},
     number = {3},
     year = {1978},
     zbl = {0392.35051},
     mrnumber = {506999},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1978_4_5_3_527_0/}
}
Hess, Peter. Nonlinear perturbations of linear elliptic and parabolic problems at resonance : existence of multiple solutions. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 5 (1978) no. 3, pp. 527-537. http://www.numdam.org/item/ASNSP_1978_4_5_3_527_0/

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