Caesar, Bellum Gallicum 1.19, 1.47, 1.53, 7.8, 7.65; Ronald Syme, The Provincial at Rome (University of Exeter Press, 1999), p. 65 online; Ramsay MacMullen, Romanization in the Time of Augustus (Yale University Press, 2000), p. 99 online and pp. 166–167, note 48.
