@ARTICLE{7452265,
  author={Butun, Ismail and Erol-Kantarci, Melike and Kantarci, Burak and Song, Houbing},
  journal={IEEE Communications Magazine}, 
  title={Cloud-centric multi-level authentication as a service for secure public safety device networks}, 
  year={2016},
  volume={54},
  number={4},
  pages={47-53},
  doi={10.1109/MCOM.2016.7452265}}