@article{Berstel_2002,
    doi = {10.1007/s00236-002-0085-4},
    url = {https://doi.org/10.1007%2Fs00236-002-0085-4},
    year = {2002},
    month = {aug},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {38},
    number = {9},
    pages = {649--671},
    author = {Jean Berstel and Luc Boasson},
    title = {Formal properties of {XML} grammars and languages},
    journal = {Acta Informatica}
}

@article{Berstel_2002, doi = {10.1007/s00236-002-0085-4}, url = {https://doi.org/10.1007%2Fs00236-002-0085-4}, year = {2002}, month = {aug}, publisher = {Springer Science and Business Media {LLC}}, volume = {38}, number = {9}, pages = {649--671}, author = {Jean Berstel and Luc Boasson}, title = {Formal properties of {XML} grammars and languages}, journal = {Acta Informatica} }