@article{10_4171_ifb_91,
     author = {S. Challal and Abdeslem Lyaghfouri},
     title = {A filtration problem through a heterogeneous porous medium},
     journal = {Interfaces and free boundaries},
     pages = {55--79},
     year = {2004},
     volume = {6},
     number = {1},
     doi = {10.4171/ifb/91},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ifb/91/}
}