@article{1649,
  author = {Minghui Shi and Xuemin Shen and Jon Mark and Dongmei Zhao and Yixin Jiang},
  title = {User authentication and undeniable billing support for agent-based roaming service in WLAN/cellular integrated mobile networks},
  year = {2008},
  journal = {Computer Networks},
  volume = {52},
  number = {9},
  pages = {1693-1702},
  publisher = {Elsevier},
}