@article{1450,
  author = {Rongxing Lu and Xiaodong Lin and Haojin Zhu and Xuemin Shen and Bruno Preiss},
  title = {Pi: A practical incentive protocol for delay tolerant networks},
  year = {2010},
  journal = {IEEE Transactions on Wireless Communications},
  volume = {9},
  number = {4},
  publisher = {IEEE},
}