@ARTICLE {6278,
author={D. Qiu Qiu and L. Li and X. Zou and P. Mateus and J. Gruska},
doi={10.1007/s00236-011-0139-6},
journal={Acta Informatica},
title={Multi-letter quantum finite automata: Decidability of the equivalence and minimization of states.},
year={2011},
month={April},
volume={48},
number={5-6},
pages={271-200},
ISSN={0001-5903}
}