@ARTICLE{DasHin_j1993, author = {J{\"u}rgen~Dassow and Friedhelm~Hinz}, title = {Decision problems and regular chain code picture languages}, journal = dam, year = 1993, volume = 45, number = 1, pages = {29--49}, url = {http://dx.doi.org/10.1016/0166-218X(93)90138-E} }