Appian, Civil Wars, 1:116; Plutarch, Crassus, 8:2. Note: Spartacus's status as an auxilia is taken from the Loeb edition of Appian translated by Horace White, which states “…who had once served as a soldier with the Romans…”. However, the translation by John Carter in the Penguin Classics version reads: “…who had once fought against the Romans and after being taken prisoner and sold…”.