no. 4
On elliptic equations with piecewise constant coefficients. II
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 26 (1972) no. 4, pp. 839-870. 
@article{ASNSP_1972_3_26_4_839_0,
     author = {Lorenzi, Alfredo},
     title = {On elliptic equations with piecewise constant coefficients. II},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {839--870},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 26},
     number = {4},
     year = {1972},
     zbl = {0252.35019},
     mrnumber = {382836},
     language = {en},
     url = {archive.numdam.org/item/ASNSP_1972_3_26_4_839_0/}
}
Lorenzi, A. On elliptic equations with piecewise constant coefficients. II. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 3, Tome 26 (1972) no. 4, pp. 839-870. http://archive.numdam.org/item/ASNSP_1972_3_26_4_839_0/

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