@ARTICLE{Das_j1984_a, author = {J{\"u}rgen~Dassow}, title = {On some extensions of {R}ussian parallel context-free grammars}, journal = actacybern, year = 1984, volume = 6, number = 4, pages = {355--360}, url = {http://www.inf.u-szeged.hu/actacybernetica/prevvols/6_4/6_4.pdf} }