@ARTICLE{8714083,
  author={X. {Wang} and H. {Dai} and W. {Wang} and J. {Zheng} and N. {Yu} and G. {Chen} and W. {Dou} and X. {Wu}},
  journal={IEEE Transactions on Mobile Computing}, 
  title={Practical Heterogeneous Wireless Charger Placement with Obstacles}, 
  year={2020},
  volume={19},
  number={8},
  pages={1910-1927},}