@article{AM2_1992__44_1_137480,
     author = {Antonio Costa and Luigi Grasselli},
     title = {Universal coverings of {PL-mainfolds} via coloured graphs.},
     journal = {Aequationes mathematicae},
     pages = {60--71},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1992},
     zbl = {0764.57004},
     url = {http://geodesic.mathdoc.fr/item/AM2_1992__44_1_137480/}
}