Juraj HromkovicGeorg Schnitger On the Power of Las Vegas II: Two-Way Finite Automata Electronic Colloquium on Computational Complexity (ECCC) 1999 7 6 db/journals/eccc/eccc6.html#ECCC-TR99-007 http://eccc.hpi-web.de/eccc-reports/1999/TR99-007/index.html