@article{H_jek_2006,
    doi = {10.1016/j.fss.2005.10.004},
    url = {https://doi.org/10.1016%2Fj.fss.2005.10.004},
    year = {2006},
    month = {mar},
    publisher = {Elsevier {BV}},
    volume = {157},
    number = {5},
    pages = {597--603},
    author = {Petr H{\'{a}}jek},
    title = {What is mathematical fuzzy logic},
    journal = {Fuzzy Sets and Systems}
}

@article{H_jek_2006, doi = {10.1016/j.fss.2005.10.004}, url = {https://doi.org/10.1016%2Fj.fss.2005.10.004}, year = {2006}, month = {mar}, publisher = {Elsevier {BV}}, volume = {157}, number = {5}, pages = {597--603}, author = {Petr H{\'{a}}jek}, title = {What is mathematical fuzzy logic}, journal = {Fuzzy Sets and Systems} }