Moller, F., Jančar, P., Kučera, A., & Sawa, Z. (2004). DP lower bounds for equivalence-checking and model-checking of one-counter automata. Information and Computation, 188(1), p. 1. doi:10.1016/S0890-5401(03)00171-8

Moller, Faron, Petr Jančar, Antonı́n Kučera, and Zdeněk Sawa. "DP Lower Bounds for Equivalence-checking and Model-checking of One-counter Automata." Information and Computation 188, no. 1 (2004): 1.

Moller, Faron, Petr Jančar, Antonı́n Kučera, and Zdeněk Sawa. "DP Lower Bounds for Equivalence-checking and Model-checking of One-counter Automata." Information and Computation 188.1 (2004): 1.