@article{IM_1981__65_142855,
     author = {K. Bongartz and P. Gabriel},
     title = {Covering {Spaces} in {Representation-Theory.}},
     journal = {Inventiones mathematicae},
     pages = {331--378},
     publisher = {mathdoc},
     volume = {65},
     year = {1981},
     zbl = {0482.16026},
     url = {http://geodesic.mathdoc.fr/item/IM_1981__65_142855/}
}