@article{DMTCS_2014_16_1_a3,
     author = {Costa, Jos\'e Carlos},
     title = {Canonical forms for free \ensuremath{\kappa}-semigroups},
     journal = {Discrete mathematics & theoretical computer science},
     publisher = {mathdoc},
     volume = {16},
     number = {1},
     year = {2014},
     doi = {10.46298/dmtcs.1247},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.46298/dmtcs.1247/}
}