@article{SLC_1986_14_a5,
     author = {Gareth Jones},
     title = {Enumerating {Regular} {Maps} and {Normal} {Subgroups} of the {Modular} {Group}},
     journal = {S\'eminaire lotharingien de combinatoire},
     publisher = {mathdoc},
     volume = {14},
     year = {1986},
     url = {http://geodesic.mathdoc.fr/item/SLC_1986_14_a5/}
}