@article{Appel_2001,
    doi = {10.1145/504709.504712},
    url = {https://doi.org/10.1145%2F504709.504712},
    year = {2001},
    month = {sep},
    publisher = {Association for Computing Machinery ({ACM})},
    volume = {23},
    number = {5},
    pages = {657--683},
    author = {Andrew W. Appel and David McAllester},
    title = {An indexed model of recursive types for foundational proof-carrying code},
    journal = {{ACM} Transactions on Programming Languages and Systems}
}

@article{Appel_2001, doi = {10.1145/504709.504712}, url = {https://doi.org/10.1145%2F504709.504712}, year = {2001}, month = {sep}, publisher = {Association for Computing Machinery ({ACM})}, volume = {23}, number = {5}, pages = {657--683}, author = {Andrew W. Appel and David McAllester}, title = {An indexed model of recursive types for foundational proof-carrying code}, journal = {{ACM} Transactions on Programming Languages and Systems} }