@article{ITA_1976__10_2_33_0, author = {Brzozowski, Janusz A.}, title = {Hierarchies of aperiodic languages}, journal = {Revue fran\c{c}aise d'automatique informatique recherche op\'erationnelle. Informatique th\'eorique}, pages = {33--49}, publisher = {Dunod-Gauthier-Villars}, address = {Paris}, volume = {10}, number = {R2}, year = {1976}, mrnumber = {428813}, language = {en}, url = {http://www.numdam.org/item/ITA_1976__10_2_33_0/} }