@article{shirali2007easy,
  author  = {Shirali-Shahreza, Sajad and Shirali-Shahreza, Mohammad and Manzuri-Shalmani, Mohammad Taghi},
  title   = {Easy and Secure Login by {CAPTCHA}},
  journal = {International Reviews on Computers and Software},
  volume  = {2},
  number  = {4},
  pages   = {393--400},
  year    = {2007},
  month   = jul,
  url	  = {https://www.praiseworthyprize.org/jsm/index.php?journal=ireit&page=article&op=view&path%5B%5D=69}
}