S. Ahmad, A. Battle, Z. Malkani, and S. Kamvar. Proceedings of the 24th annual ACM symposium on User interface software and technology, page 53--64. New York, NY, USA, ACM, (2011)
G. Little, L. Chilton, M. Goldman, and R. Miller. Proceedings of the 23nd annual ACM symposium on User interface software and technology, page 57--66. New York, NY, USA, ACM, (2010)