Andris Ambainis Arnolds Kikusts Exact Results for Accepting Probabilities of Quantum Automata. 135-147 2001 conf/mfcs/2001 MFCS http://link.springer.de/link/service/series/0558/bibs/2136/21360135.htm db/conf/mfcs/mfcs2001.html#AmbainisK01