no. 1
The inhomogeneous dam problem with discontinuous permeability
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 14 (1987) no. 1, pp. 49-77. 
@article{ASNSP_1987_4_14_1_49_0,
     author = {Friedman, Avner and Huang, Shao-Yun},
     title = {The inhomogeneous dam problem with discontinuous permeability},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {49--77},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 14},
     number = {1},
     year = {1987},
     zbl = {0644.35097},
     mrnumber = {937536},
     language = {en},
     url = {archive.numdam.org/item/ASNSP_1987_4_14_1_49_0/}
}
Friedman, Avner; Huang, Shao-Yun. The inhomogeneous dam problem with discontinuous permeability. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 14 (1987) no. 1, pp. 49-77. http://archive.numdam.org/item/ASNSP_1987_4_14_1_49_0/

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