@InCollection{FerSti_j2001_c, author = {Henning~Fernau and Ralf~Stiebe}, title = {{Valence Grammars with Target Sets}}, booktitle = {{Words, Semigroups, and Transductions}}, pages = {129--140}, publisher = worldsci, year = 2001, editor = {Masami~Ito and Gheorghe~P\u{a}un and Sheng~Yu} }