@article{10_1017_S0017089502010121,
     author = {Hoffmann, Michael and Thomas, Richard M.},
     title = {Automaticity and commutative semigroups},
     journal = {Glasgow mathematical journal},
     pages = {167--176},
     year = {2002},
     volume = {44},
     number = {1},
     doi = {10.1017/S0017089502010121},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089502010121/}
}