Diana Gabaldon (2015). “The Outlander Series 8-Book Bundle: Outlander, Dragonfly in Amber, Voyager, Drums of Autumn, The Fiery Cross, A Breath of Snow and Ashes, An Echo in the Bone, Written in My Own Heart's Blood”, p.19, Dell
David Hume (1826). “The history of England: From the invasion of Julius Caesar to the revolution of 1688 : To which is prefixed a short account of his life, written by himself”, p.187