@incollection{Kunc_2011,
    doi = {10.1007/978-3-642-22321-1_28},
    url = {https://doi.org/10.1007%2F978-3-642-22321-1_28},
    year = {2011},
    publisher = {Springer Berlin Heidelberg},
    pages = {324--336},
    author = {Michal Kunc and Alexander Okhotin},
    title = {Describing Periodicity in Two-Way Deterministic Finite Automata Using Transformation Semigroups},
    booktitle = {Developments in Language Theory}
}

@incollection{Kunc_2011, doi = {10.1007/978-3-642-22321-1_28}, url = {https://doi.org/10.1007%2F978-3-642-22321-1_28}, year = {2011}, publisher = {Springer Berlin Heidelberg}, pages = {324--336}, author = {Michal Kunc and Alexander Okhotin}, title = {Describing Periodicity in Two-Way Deterministic Finite Automata Using Transformation Semigroups}, booktitle = {Developments in Language Theory} }