@article{Engelfriet_2009,
    doi = {10.1016/j.jcss.2009.01.001},
    url = {https://doi.org/10.1016%2Fj.jcss.2009.01.001},
    year = {2009},
    month = {aug},
    publisher = {Elsevier {BV}},
    volume = {75},
    number = {5},
    pages = {271--286},
    author = {Joost Engelfriet and Sebastian Maneth and Helmut Seidl},
    title = {Deciding equivalence of top{\textendash}down {XML} transformations in polynomial time},
    journal = {Journal of Computer and System Sciences}
}

@article{Engelfriet_2009, doi = {10.1016/j.jcss.2009.01.001}, url = {https://doi.org/10.1016%2Fj.jcss.2009.01.001}, year = {2009}, month = {aug}, publisher = {Elsevier {BV}}, volume = {75}, number = {5}, pages = {271--286}, author = {Joost Engelfriet and Sebastian Maneth and Helmut Seidl}, title = {Deciding equivalence of top{\textendash}down {XML} transformations in polynomial time}, journal = {Journal of Computer and System Sciences} }