@article{Greibach_1972,
    doi = {10.1016/0012-365x(72)90013-1},
    url = {https://doi.org/10.1016%2F0012-365x%2872%2990013-1},
    year = {1972},
    month = {jul},
    publisher = {Elsevier {BV}},
    volume = {2},
    number = {4},
    pages = {347--355},
    author = {S.A. Greibach},
    title = {A generalization of Parikh{\textquotesingle}s semilinear theorem},
    journal = {Discrete Mathematics}
}

@article{Greibach_1972, doi = {10.1016/0012-365x(72)90013-1}, url = {https://doi.org/10.1016%2F0012-365x%2872%2990013-1}, year = {1972}, month = {jul}, publisher = {Elsevier {BV}}, volume = {2}, number = {4}, pages = {347--355}, author = {S.A. Greibach}, title = {A generalization of Parikh{\textquotesingle}s semilinear theorem}, journal = {Discrete Mathematics} }