@article{JIS_2009__12_2_a4,
     author = {Pakapongpun,  Apisit and Ward,  Thomas B.},
     title = {Functorial orbit counting},
     journal = {Journal of integer sequences},
     year = {2009},
     volume = {12},
     number = {2},
     zbl = {1254.37020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2009__12_2_a4/}
}