@article{YLL14CIS,
  author    = {Wuyi Yu and
               Maoqing Li and
               Xin Li},
  title     = {Optimizing Pyramid Visibility Coverage for Autonomous Robots in 3D Environment},
  journal   = {Control and Intelligent System},
  volume    = {42},
  number    = {1},
  year      = {2014},
  pages     = {9-15},
}