Abdal-kadhim, Ali Mohammed, and kok Swee Leong. “Hybrid Energy Harvesting Scheme Using Piezoelectric and Thermoelectric for Wireless Sensor Nodes”. International Journal of Integrated Engineering, vol. 11, no. 1, May 2019, https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/2348.