Bauer, Dieter Division Prof. Dr. Christoph H. Keitel, MPI for Nuclear Physics, Max Planck Society;
http://iopscience.iop.org/1742-6596/11/1/017/ (Publisher version)
Bauer, D., & Mulser, P. (2005). Irreversible energy gain by linear and nonlinear oscillators. Journal of Physics: Conference Series, 11(1), 169-179. doi:10.1088/1742-6596/11/1/017.