@article{JAC_1992__1_4_a4,
     author = {Bj\"orner, Anders and Lov\'asz, L\'aszl\'o},
     title = {Chip-firing games on directed graphs},
     journal = {Journal of Algebraic Combinatorics},
     pages = {305--328},
     publisher = {mathdoc},
     volume = {1},
     number = {4},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_1992__1_4_a4/}
}