A. M. Wahl, Mechanical Springs, 1963.

, European standards related to torsion springs, pp.335-3931, 2002.

, Midwest Road, vol.106, pp.60523-1335, 2001.

M. Shimoseki, T. Hamano, and T. Imaizumi, Elementary analyses, helical torsion springs, FEM for springs, pp.125-128, 2003.