@InProceedings{Sti_j2001, author = {Ralf~Stiebe}, title = {Positive Valence Grammars}, booktitle = {11.~Theorietag Automaten und Formale Sprachen}, pages = {103--106}, year = 2001, editor = {J{\"u}rgen~Dassow and Bernd~Reichel}, organization = {Otto-von-Guericke-Universit{\"a}t Magdeburg, Fakult{\"a}t f{\"u}r Informatik} }