Talib, N. H. H. A., et al. “Comprehensive Review on Effective Strategies and Key Factors for High Performance Piezoelectric Energy Harvester at Low Frequency”. International Journal of Automotive and Mechanical Engineering, vol. 16, no. 4, Dec. 2019, pp. 7181-10, doi:10.15282/ijame.16.4.2019.03.0537.