@article{Selman_1972,
    doi = {10.1007/bf02945004},
    url = {https://doi.org/10.1007%2Fbf02945004},
    year = {1972},
    month = {dec},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {2},
    number = {1},
    pages = {20--32},
    author = {A. Selman},
    title = {Completeness of calculii for axiomatically defined classes of algebras},
    journal = {Algebra Universalis}
}

@article{Selman_1972, doi = {10.1007/bf02945004}, url = {https://doi.org/10.1007%2Fbf02945004}, year = {1972}, month = {dec}, publisher = {Springer Science and Business Media {LLC}}, volume = {2}, number = {1}, pages = {20--32}, author = {A. Selman}, title = {Completeness of calculii for axiomatically defined classes of algebras}, journal = {Algebra Universalis} }