@article{10_1017_S0017089500009903,
     author = {Lam, Clement S.},
     title = {Some characterizations of the hereditary pretorsion class of semigroup automata},
     journal = {Glasgow mathematical journal},
     pages = {327--337},
     year = {1993},
     volume = {35},
     number = {3},
     doi = {10.1017/S0017089500009903},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500009903/}
}