@incollection{Pollack_1995,
    doi = {10.1007/3-540-60579-7_8},
    url = {https://doi.org/10.1007%2F3-540-60579-7_8},
    year = {1995},
    publisher = {Springer Berlin Heidelberg},
    pages = {140--161},
    author = {Robert Pollack},
    title = {On extensibility of proof checkers},
    booktitle = {Lecture Notes in Computer Science}
}

@incollection{Pollack_1995, doi = {10.1007/3-540-60579-7_8}, url = {https://doi.org/10.1007%2F3-540-60579-7_8}, year = {1995}, publisher = {Springer Berlin Heidelberg}, pages = {140--161}, author = {Robert Pollack}, title = {On extensibility of proof checkers}, booktitle = {Lecture Notes in Computer Science} }