1. L. Jin, J.H. Wang, W.Y. Hu. Basic Automatation,Vol. 2 (1996), p.12.
2. J.F. Qiao, X.B. Wang, T.Y. Chai. Control Theory and Applications, Vol. 17(2000), p.393.
3. Q.D. Zhang, X.L. Chen. Journal of University of Science and Technology Beijing, Vol. 18(1996), p.347.
4. G.D. Wang: Shape control and shape theory, metallurgical industry press, Beijing (1986).
5. V B Ginzburg: High-quality steel rolling theory and practice, Marcel Deker. Inc, New York (1993).