1. Shang, H. J., Design and Computation of Valve-Cam Mechanism. Fudan University Press, 1988 (in Chinese).
2. Qi, C. S., ?The study of some problems in valve mechanism?, M. S. Thesis, Tianjin University, China, 1984 (in Chinese).
3. Huo, Q. Z. and Tang, J. S., ?Using equation of variable parameter to study vibration of valve mechanism at internal combustion engine?, The Academic Conference on Vibration and Noise of Internal combustion Engine, Shanxi, 1988 (in Chinese).
4. Tang, J. S., ?Nonlinear dynamic calculation of valve train by multiple scales method?, Chinese Internal Combustion Engine Engineering 7, 1986, 61?65.
5. Holmes, P. J., ?Center manifolds, normal forms and bifurcations of vector fields with application to coupling between periodic and steady motions?, Physica D 2, 1981, 449?481.