@article{Levy_2008,
    doi = {10.1137/050645403},
    url = {https://doi.org/10.1137%2F050645403},
    year = {2008},
    month = {jan},
    publisher = {Society for Industrial {\&} Applied Mathematics ({SIAM})},
    volume = {38},
    number = {3},
    pages = {1113--1140},
    author = {Jordi Levy and Manfred Schmidt-Schau{\ss} and Mateu Villaret},
    title = {The Complexity of Monadic Second-Order Unification},
    journal = {{SIAM} Journal on Computing}
}

@article{Levy_2008, doi = {10.1137/050645403}, url = {https://doi.org/10.1137%2F050645403}, year = {2008}, month = {jan}, publisher = {Society for Industrial {\&} Applied Mathematics ({SIAM})}, volume = {38}, number = {3}, pages = {1113--1140}, author = {Jordi Levy and Manfred Schmidt-Schau{\ss} and Mateu Villaret}, title = {The Complexity of Monadic Second-Order Unification}, journal = {{SIAM} Journal on Computing} }