@ARTICLE{DasFerPau_j1999, author = {J{\"u}rgen~Dassow and Henning~Fernau and Gheorghe~P\u{a}un}, title = {On the leftmost derivation in matrix grammars}, journal = ijfcs, year = 1999, volume = 10, number = 1, pages = {61--79}, url = {http://dx.doi.org/10.1142/S012905419900006X} }