Suetonius, The Lives of Twelve Caesars, Life of Caligula 45–47.
R.W. Davies, "The Abortive Invasion of Britain by Gaius", Historia 15 (1966), 124–128; S.J.V.Malloch, 'Gaius on the Channel Coast', Classical Quarterly 51 (2001) 551-56; See Suetonius, The Lives of Twelve Caesars, Life of Caligula 44.