@Unpublished{ADM08,
    Author       = "Avigad, J. and Dean, E. and Mumma, J.",
    Year         = "2008",
    Title        = "{A Formal System for Euclid's Elements}",
    Note         = "{10.48550/arXiv.0810.4315v3}",
    Comment      = "TPTPRef"
}