1. Vibration Problems in Engineering;Timoshenko,1955
2. Forced vibrations with non-linear spring constants;Den Hartog;Journal of Applied Mechanics, Transactions of the American Society of Mechanical Engineers,1932
3. Forced vibration in nonlinear systems with various combinations of linear springs;Den Hartog;Journal of Applied Mechanics, Transactions of the American Society of Mechanical Engineers,1936
4. Steady state vibrations in systems having arbitrary restoring and damping forces;Klotter,1953
5. Branching phenomena for periodic solutions of non-autonomous piecewise linear systems;Loud;International Journal of Non-Linear Mechanics,1968