Alireza Keshmiri and  Shahriar Bagheri and  Nan Wu,  Simulation-Based Optimization of a Non-Uniform Piezoelectric Energy Harvester with Stack Boundary.   journal   = {International Journal of Mechanical and Materials Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2019, vol. 151(7). 500 - 505
    [viewed 20 November 2019]. Available from: https://publications.waset.org/pdf/10010589.