1. Sheet metal working in the bronze age and iron age in southern central Europe;Fries-Knoblach,1999
2. Engineering Study of Sheet Bending, Verlag des Deutschen Polytechnischen Vereins, Böhmen;Ludwik;Technische Blätter,1903
3. Het Vrijbuigen van Plaat in de Kleinseriefabricage;Streppel;MB-Produktietechniek,1997
4. L.J. de Vin, Computer aided process planning for the bending of sheet metal components, Doctoral Dissertation, Enschede, The Netherlands, 1994, ISBN 90-9007217-9.
5. Handbook of Metal Forming;Lange,1985