@article{Stone_2006,
    doi = {10.1145/1183278.1183281},
    url = {https://doi.org/10.1145%2F1183278.1183281},
    year = {2006},
    month = {oct},
    publisher = {Association for Computing Machinery ({ACM})},
    volume = {7},
    number = {4},
    pages = {676--722},
    author = {Christopher A. Stone and Robert Harper},
    title = {Extensional equivalence and singleton types},
    journal = {{ACM} Transactions on Computational Logic}
}

@article{Stone_2006, doi = {10.1145/1183278.1183281}, url = {https://doi.org/10.1145%2F1183278.1183281}, year = {2006}, month = {oct}, publisher = {Association for Computing Machinery ({ACM})}, volume = {7}, number = {4}, pages = {676--722}, author = {Christopher A. Stone and Robert Harper}, title = {Extensional equivalence and singleton types}, journal = {{ACM} Transactions on Computational Logic} }