Yusuke Takahashi Hidehiro Nakano Toshimichi Saito Hyperchaotic spiking oscillators with periodic pulse-train input. 344-348 2005 52-II IEEE Trans. Circuits Syst. II Express Briefs 6 https://doi.org/10.1109/TCSII.2005.849002 db/journals/tcas/tcasII52.html#TakahashiNS05