@ARTICLE{DasMatPauSal_j1992, author = {J{\"u}rgen~Dassow and Alexandru~Mateescu and Gheorghe~P\u{a}un and Arto~Salomaa}, title = {Regularizing context-free languages by {AFL} operations: concatenation and Kleene closure}, journal = actacybern, year = 1992, volume = 10, number = 4, pages = {243--253}, url = {http://www.inf.u-szeged.hu/actacybernetica/vol10n4/dassow/dassow.xml} }