Andris Ambainis Richard F. Bonner Rusins Freivalds Arnolds Kikusts Probabilities to Accept Languages by Quantum Finite Automata. 174-183 http://link.springer.de/link/service/series/0558/bibs/1627/16270174.htm 1999 COCOON db/conf/cocoon/cocoon99.html#AmbainisBFK99