D. Aharonov, A. Kitaev, and N. Nisan. Quantum circuits with mixed states. Proceedings of STOC'98, pp. 20-30.
 A. Ambainis, E. Bach, A. Nayak, A. Vishwanath, J. Watrous, One-dimensional quantum walks. Proceedings of STOC'01.
 F. Chen, L. Lovasz and I. Pak, Lifting Markov chains to speed up mixing, Proceedings of STOC'99, pp. 275-281.
 A. Childs, E. Farhi, S. Gutmann, An example of a difference between quantum and classical random walks. LANL preprint http://www.arxiv.org/abs/quant-ph/0103020.
 E. Farhi, S. Gutmann, Quantum computation and decision trees, Physical Review A, 58 : 915-928, 1998.
 L. Grover, A fast quantum mechanical algorithm for database search Proceedings of STOC'96, pp. 212-219.