@article{userfriendlylinecaptchas,
  title = {User Friendly Line CAPTCHAs},
  author = {A. K. B. Karunathilake and B. M. D. Balasuriya and R. G. Ragel},
  year = {2014},
  eprint = {1402.0672},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1402.0672v1},
}