Juraj Hromkovic Sebastian Seibert Thomas Wilke Translating Regular Expressions into Small epsilon-Free Nondeterministic Finite Automata. 55-66 1997 conf/stacs/1997 STACS db/conf/stacs/stacs97.html#HromkovicSW97 http://dx.doi.org/10.1007/BFb0023448