@article{Muller_1983,
    doi = {10.1016/0022-0000(83)90003-x},
    url = {https://doi.org/10.1016%2F0022-0000%2883%2990003-x},
    year = {1983},
    month = {jun},
    publisher = {Elsevier {BV}},
    volume = {26},
    number = {3},
    pages = {295--310},
    author = {David E. Muller and Paul E. Schupp},
    title = {Groups, the Theory of ends, and context-free languages},
    journal = {Journal of Computer and System Sciences}
}

@article{Muller_1983, doi = {10.1016/0022-0000(83)90003-x}, url = {https://doi.org/10.1016%2F0022-0000%2883%2990003-x}, year = {1983}, month = {jun}, publisher = {Elsevier {BV}}, volume = {26}, number = {3}, pages = {295--310}, author = {David E. Muller and Paul E. Schupp}, title = {Groups, the Theory of ends, and context-free languages}, journal = {Journal of Computer and System Sciences} }