@article{shirali2010survey,
  author  = {Shirali-Shahreza, Sajad and Shirali-Shahreza, Mohammad},
  title   = {A Survey of Human Interactive Proof Systems},
  journal = {International Journal of Innovative Computing, Information and Control},
  volume  = {6},
  number  = {3(A)},
  pages   = {855--874},
  year    = {2010},
  month   = mar,
  url	  = {http://www.ijicic.org/08-1019-1.pdf}
}