@book{Sippu_1988,
    doi = {10.1007/978-3-642-61345-6},
    url = {https://doi.org/10.1007%2F978-3-642-61345-6},
    year = {1988},
    publisher = {Springer Berlin Heidelberg},
    author = {Seppo Sippu and Eljas Soisalon-Soininen},
    title = {Parsing Theory}
}

@book{Sippu_1988, doi = {10.1007/978-3-642-61345-6}, url = {https://doi.org/10.1007%2F978-3-642-61345-6}, year = {1988}, publisher = {Springer Berlin Heidelberg}, author = {Seppo Sippu and Eljas Soisalon-Soininen}, title = {Parsing Theory} }