@article{Knuth_1967,
    doi = {10.1016/s0019-9958(67)90564-5},
    url = {https://doi.org/10.1016%2Fs0019-9958%2867%2990564-5},
    year = {1967},
    month = {sep},
    publisher = {Elsevier {BV}},
    volume = {11},
    number = {3},
    pages = {269--289},
    author = {Donald E. Knuth},
    title = {A characterization of parenthesis languages},
    journal = {Information and Control}
}

@article{Knuth_1967, doi = {10.1016/s0019-9958(67)90564-5}, url = {https://doi.org/10.1016%2Fs0019-9958%2867%2990564-5}, year = {1967}, month = {sep}, publisher = {Elsevier {BV}}, volume = {11}, number = {3}, pages = {269--289}, author = {Donald E. Knuth}, title = {A characterization of parenthesis languages}, journal = {Information and Control} }