@article{JRAM_1981__322_152321,
     author = {Wolfgang Alt},
     title = {Singular perturbation of differential integral equations describing biased random walks.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {15--41},
     publisher = {mathdoc},
     volume = {322},
     year = {1981},
     zbl = {0437.60059},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1981__322_152321/}
}