@incollection{DasPauRoz_j1997, author = {J{\"u}rgen~Dassow and Gheorghe~P\u{a}un and Grzegorz~Rozenberg}, title = {{Grammar systems}}, booktitle = {{Handbook of Formal Languages}}, publisher = springer, year = 1997, editor = {Grzegorz~Rozenberg and Arto~Salomaa}, pages = {155-213} }