@inproceedings{collectivespatialkeywordquerying,
  title = {Collective Spatial Keyword Querying},
  author = {Xin Cao1 and Gao Cong},
  year = {2011},
  booktitle = {2011 2011 6},
  url = {https://doi.org/10.1145/1989323.1989363},
}