@article{Lyndon_1950,
    doi = {10.2307/1969375},
    url = {https://doi.org/10.2307%2F1969375},
    year = {1950},
    month = {may},
    publisher = {{JSTOR}},
    volume = {51},
    number = {3},
    pages = {707},
    author = {Roger C. Lyndon},
    title = {The Representation of Relational Algebras},
    journal = {The Annals of Mathematics}
}

@article{Lyndon_1950, doi = {10.2307/1969375}, url = {https://doi.org/10.2307%2F1969375}, year = {1950}, month = {may}, publisher = {{JSTOR}}, volume = {51}, number = {3}, pages = {707}, author = {Roger C. Lyndon}, title = {The Representation of Relational Algebras}, journal = {The Annals of Mathematics} }