STE3D-CAP: Stereoscopic 3D CAPTCHA. - Willy Susilo; Yang-Wai Chow; Hua-Yu Zhou (CANS, 2010)

CAPTCHA Challenges for Massively Multiplayer Online Games: Mini-game CAPTCHAs. - Yang-Wai Chow; Willy Susilo; Hua-Yu Zhou (CW, 2010)