B. Ur, P. Leon, L. Cranor, R. Shay, and Y. Wang. Proceedings of the Eighth Symposium on Usable Privacy and Security, page 4:1--4:15. New York, NY, USA, ACM, (2012)
J. Zhou, L. Wang, A. Akbarzadeh, and R. Yang. PROCAMS '08: Proceedings of the 5th ACM/IEEE International Workshop on Projector camera systems, page 1--7. New York, NY, USA, ACM, (2008)