P. S. Low, R. Ramlan, H. A. Ghani, and N. S. Muhammad, “Experimental Analysis on the Transduction Coefficient of a Non-Linear Electromagnetic Energy Harvesting Device with Softening Stiffness”, Int. J. Automot. Mech. Eng., vol. 17, no. 2, pp. 7816–7831, Jul. 2020.