no. 4
A nonlinear elliptic boundary value problem
Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche, Série 3, Tome 27 (1973) no. 4, pp. 707-716. 
@article{ASNSP_1973_3_27_4_707_0,
     author = {Schechter, Martin},
     title = {A nonlinear elliptic boundary value problem},
     journal = {Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche},
     pages = {707--716},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 27},
     number = {4},
     year = {1973},
     mrnumber = {369912},
     zbl = {0302.35044},
     language = {en},
     url = {http://archive.numdam.org/item/ASNSP_1973_3_27_4_707_0/}
}
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Schechter, Martin. A nonlinear elliptic boundary value problem. Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche, Série 3, Tome 27 (1973) no. 4, pp. 707-716. http://archive.numdam.org/item/ASNSP_1973_3_27_4_707_0/

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