Khang, N. V., H. M. Cuong, and N. T. Minh Tuan. “Calculation of Nonlinear Vibrations of Piecewise-Linear Systems Using the Shooting Method”. Vietnam Journal of Mechanics, vol. 34, no. 3, Sept. 2012, pp. 157-6, doi:10.15625/0866-7136/34/3/2357.