@article{SLC_1987_16_a3,
     author = {Daniel I. A. Cohen and Victor S. Miller},
     title = {On the {Four} {Color} {Problem}},
     journal = {S\'eminaire lotharingien de combinatoire},
     year = {1987},
     volume = {16},
     url = {http://geodesic.mathdoc.fr/item/SLC_1987_16_a3/}
}