40s BC
Cicero, Marcus Tullius. Laelius de Amicitia. c. 43 BC, ch. 21, sect. 80.
Cicero, Marcus Tullius. "Laelius de Amicitia." M. Tullius Ciceronis: De Re Publica, De Legibus, Cato Maior de Senectute, Laelius de Amicitia, edited by J. G. F. Powell. Oxford University Press, 2006.
Cicero, Marcus Tullius. De Divinatione [Concerning Divination]. c. 44 BC, bk. 2, ch 58, sect. 119.
Cicero, Marcus Tullius. Cato Maior de Senectute [Cato the Elder on Old Age]. c. 1885, ch. 23, sect. 85.
Cicero, Marcus Tullius. Cicero: Cato Maior de Senectute [Cato the Elder on Old Age], edited by J. G. F. Powell. Cambridge University Press, 2004.
Cicero, Marcus Tullius. Brutus. c. 46 BC, sect. 71.
Cicero, Marcus Tullius. "Brutus." Cicero: Brutus and Orator, translated by Robert A. Kaster. Oxford University Press, 2020, sect. 71.
Cicero, Marcus Tullius. De Divinatione [Concerning Divination]. c. 44 BC, bk. 1, ch. 52, sect. 118.
Sallust. Bellum Catilinae [War of Catiline]. c. 43–40 BC.
Sallust. "The War with Catiline." The War with Catiline and The War with Jugurtha, translated by John T. Ramsey J. C. Rolfe. Harvard University Press, 2013.
Quintus Ennius. Quoted in De Natura Deorum [On the Nature of the Gods], written by Cicero. c. 45 BC, bk. 1.
Quintus Ennius. Quoted in The Nature of the Gods, written by Cicero, translated by P. G. Walsh. Oxford University Press, 2008, bk. 1.
Sallust. Bellum Catilinae [War of Catiline]. c. 43–40 BC.
Sallust. "The War with Catiline." The War with Catiline and The War with Jugurtha, translated by John T. Ramsey J. C. Rolfe. Harvard University Press, 2013.