@article{ITA_1980__14_2_169_0,
     author = {Sommerhalder, R.},
     title = {Classes of languages proof against regular pumping},
     journal = {RAIRO. Informatique th\'eorique},
     pages = {169--180},
     publisher = {EDP-Sciences},
     volume = {14},
     number = {2},
     year = {1980},
     mrnumber = {581675},
     zbl = {0449.68035},
     language = {en},
     url = {http://www.numdam.org/item/ITA_1980__14_2_169_0/}
}