@article{Hopcroft_2001,
    doi = {10.1145/568438.568455},
    url = {https://doi.org/10.1145%2F568438.568455},
    year = {2001},
    month = {mar},
    publisher = {Association for Computing Machinery ({ACM})},
    volume = {32},
    number = {1},
    pages = {60--65},
    author = {John E. Hopcroft and Rajeev Motwani and Jeffrey D. Ullman},
    title = {Introduction to automata theory, languages, and computation, 2nd edition},
    journal = {{ACM} {SIGACT} News}
}

@article{Hopcroft_2001, doi = {10.1145/568438.568455}, url = {https://doi.org/10.1145%2F568438.568455}, year = {2001}, month = {mar}, publisher = {Association for Computing Machinery ({ACM})}, volume = {32}, number = {1}, pages = {60--65}, author = {John E. Hopcroft and Rajeev Motwani and Jeffrey D. Ullman}, title = {Introduction to automata theory, languages, and computation, 2nd edition}, journal = {{ACM} {SIGACT} News} }