@article{Harju_2002,
    doi = {10.1006/jcss.2002.1836},
    url = {https://doi.org/10.1006%2Fjcss.2002.1836},
    year = {2002},
    month = {sep},
    publisher = {Elsevier {BV}},
    volume = {65},
    number = {2},
    pages = {278--294},
    author = {Tero Harju and Oscar Ibarra and Juhani Karhumäki and Arto Salomaa},
    title = {Some Decision Problems Concerning Semilinearity and Commutation},
    journal = {Journal of Computer and System Sciences}
}

@article{Harju_2002, doi = {10.1006/jcss.2002.1836}, url = {https://doi.org/10.1006%2Fjcss.2002.1836}, year = {2002}, month = {sep}, publisher = {Elsevier {BV}}, volume = {65}, number = {2}, pages = {278--294}, author = {Tero Harju and Oscar Ibarra and Juhani Karhumäki and Arto Salomaa}, title = {Some Decision Problems Concerning Semilinearity and Commutation}, journal = {Journal of Computer and System Sciences} }