@article{JIS_2015__18_4_a2,
     author = {Walsh, Timothy R.},
     title = {Space-efficient generation of nonisomorphic maps and hypermaps},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {18},
     number = {4},
     year = {2015},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2015__18_4_a2/}
}