@article{AM2_1981__23_136887,
     author = {I.P. Goulden and D.M. Jackson},
     title = {Sequence enumeration.},
     journal = {Aequationes mathematicae},
     pages = {6--23},
     publisher = {mathdoc},
     volume = {23},
     year = {1981},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AM2_1981__23_136887/}
}