1. S. Roggendorff, J. Haeusler, Welding and Metal Fabrication 353 (July/Aug.) (1979).
2. Press and Shear Machinery Co. Ltd, Ind Equipment News (UK) 56 (Mid-March) (1974).
3. S.R. Bala, L. Malik, Welding and Metal Fabrication, 100 (March) (1983).
4. The bending of plate using a three-roll pyramid type plate bending machine