@ARTICLE{DasMit_j2000, AUTHOR = {J{\"u}rgen~Dassow and Victor~Mitrana}, TITLE = {Finite Automata over Free Groups}, JOURNAL = ijalgcomp, YEAR = 2000, VOLUME = 10, number = 6, PAGES = {725--737}, url = {http://dx.doi.org/10.1142/S0218196700000315} }