Security and Usability Challenges of Moving-Object CAPTCHAs: Decoding Codewords in Motion. - Yi Xu 006; Gerardo Reynaga; Sonia Chiasson; Jan-Michael Frahm; Fabian Monrose; Paul C. van Oorschot (USENIX Security Symposium, 2012)

The Usability of CAPTCHAs on Smartphones. - Gerardo Reynaga; Sonia Chiasson (SECRYPT, 2013)

Security Analysis and Related Usability of Motion-Based CAPTCHAs: Decoding Codewords in Motion. - Yi Xu 006; Gerardo Reynaga; Sonia Chiasson; Jan-Michael Frahm; Fabian Monrose; Paul C. van Oorschot (IEEE Trans. Dependable Secur. Comput., 2014)

Heuristics for the evaluation of captchas on smartphones. - Gerardo Reynaga; Sonia Chiasson; Paul C. van Oorschot (BCS HCI, 2015)