@inproceedings{ICPR-v1-2006-Liao,
	author        = "Wen-Hung Liao",
	booktitle     = "{Proceedings of the 18th International Conference on Pattern Recognition, Volume 1}",
	doi           = "10.1109/ICPR.2006.40",
	isbn          = "0-7695-2521-0",
	pages         = "1179--1183",
	publisher     = "{IEEE Computer Society}",
	title         = "{A Captcha Mechanism By Exchange Image Blocks}",
	year          = 2006,
}