@article{Boja_czyk_2009,
    doi = {10.1145/1516512.1516515},
    url = {https://doi.org/10.1145%2F1516512.1516515},
    year = {2009},
    month = {may},
    publisher = {Association for Computing Machinery ({ACM})},
    volume = {56},
    number = {3},
    pages = {1--48},
    author = {Mikoaj Boja{\'{n}}czyk and Anca Muscholl and Thomas Schwentick and Luc Segoufin},
    title = {Two-variable logic on data trees and {XML} reasoning},
    journal = {Journal of the {ACM}}
}

@article{Boja_czyk_2009, doi = {10.1145/1516512.1516515}, url = {https://doi.org/10.1145%2F1516512.1516515}, year = {2009}, month = {may}, publisher = {Association for Computing Machinery ({ACM})}, volume = {56}, number = {3}, pages = {1--48}, author = {Mikoaj Boja{\'{n}}czyk and Anca Muscholl and Thomas Schwentick and Luc Segoufin}, title = {Two-variable logic on data trees and {XML} reasoning}, journal = {Journal of the {ACM}} }