@article{JIS_2005__8_2_a3,
     author = {Moreira,  Nelma and Reis,  Rog\'erio},
     title = {On the density of languages representing finite set partitions},
     journal = {Journal of integer sequences},
     year = {2005},
     volume = {8},
     number = {2},
     zbl = {1064.05017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2005__8_2_a3/}
}