Deterministic Two-Way One-Head Pushdown Automata are Very Powerful.

Burkhard Monien Deterministic Two-Way One-Head Pushdown Automata are Very Powerful. 239-242 1984 18 Inf. Process. Lett. 5 db/journals/ipl/ipl18.html#Monien84 http://dx.doi.org/10.1016/0020-0190(84)90001-2