@article{NUMA_1991__60_4_133599,
     author = {Willi J\"ager and Jozef Kacur},
     title = {Solution of porous medium type systems by linear approximation schemes.},
     journal = {Numerische Mathematik},
     pages = {407--428},
     publisher = {mathdoc},
     volume = {60},
     number = {4},
     year = {1991},
     zbl = {0744.65060},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1991__60_4_133599/}
}