Hans-Jörg Kreowski Giorgio Busatto Renate Klempien-Hinrichs Peter Knirsch Sabine Kuske Structured Modeling with GRACE. 2001 51 Electr. Notes Theor. Comput. Sci. http://www.elsevier.com/gej-ng/31/29/23/116/25/show/Products/notes/index.htt#017 db/journals/entcs/entcs51.html#KreowskiBKKK01