@article{AM2_1986__31_137142,
     author = {Ronald C. Read},
     title = {On the enumeration of a class of plane multigraphs.},
     journal = {Aequationes mathematicae},
     pages = {47--63},
     year = {1986},
     volume = {31},
     zbl = {0605.05021},
     url = {http://geodesic.mathdoc.fr/item/AM2_1986__31_137142/}
}