Abdal-Kadhim, Ali Mohammed, Kok Swee Leong, and Lau Kok Tee. 2016. “Impact Based Piezoelectric Energy Harvesting: Effect of Single Step’s Force and Velocity”. Journal of Telecommunication, Electronic and Computer Engineering (JTEC) 8 (5):125-29. https://jtec.utem.edu.my/jtec/article/view/865.