Andris Ambainis Arnolds Kikusts Maris Valdats On the Class of Languages Recognizable by 1-Way Quantum Finite Automata. 75-86 2001 conf/stacs/2001 STACS http://link.springer.de/link/service/series/0558/bibs/2010/20100075.htm db/conf/stacs/stacs2001.html#AmbainisKV01