Manzoor, A. ., A. . Wahid, M. . Ali Shah, A. . Akhunzada, and F. . Fayyaz Qureshi. “Secure Login Using Multi-Tier Authentication Schemes in Fog Computing”. EAI Endorsed Transactions on Internet of Things, vol. 3, no. 11, July 2017, p. e5, doi:10.4108/eai.26-3-2018.154382.