@article{Engelfriet_2015,
    doi = {10.1007/s00236-015-0224-3},
    url = {https://doi.org/10.1007%2Fs00236-015-0224-3},
    year = {2015},
    month = {mar},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {52},
    number = {7-8},
    pages = {559--571},
    author = {Joost Engelfriet},
    title = {Two-way pebble transducers for partial functions and their composition},
    journal = {Acta Informatica}
}

@article{Engelfriet_2015, doi = {10.1007/s00236-015-0224-3}, url = {https://doi.org/10.1007%2Fs00236-015-0224-3}, year = {2015}, month = {mar}, publisher = {Springer Science and Business Media {LLC}}, volume = {52}, number = {7-8}, pages = {559--571}, author = {Joost Engelfriet}, title = {Two-way pebble transducers for partial functions and their composition}, journal = {Acta Informatica} }