53. De inst. orat., III, iv, 6.
58. Ad Herennium, I, 2; Cicero, De inventione, I, vii. De oratore, I, 142; Quintilian, De inst. orat., III, iii, i.
59. Aristotle, Rhetoric, III, xiii-xix; Cicero, Partit. orat., 15.
61. Cicero, De oratore, I. 143; Quint., De inst. orat., III, ix.