@article{Zhao:GISWHU2009,
  title={A New K-Nearest Neighbors Search Algorithm Based on 3D Cell Grids},
  author={Zhao, Jianhui and Long, Chengjiang and Ding, Yihua and Yuan, Zhiyong},
  journal={Geomatics and Information Science of Wuhan University (in Chinese)},
  volume={34},
  number={5},
  pages={615--618},
  year={2009}
}