1. William of Newburgh, Historia Rerum Anglicarum in Chronicles of the Reigns of Stephen, Henry II., and Richard I, vol. 2, ed. Richard Howlett, Rolls Series 82 (London: Longman, 1884–5), Book Five, Chapter 22. English translation taken from Joseph Stevenson, The Church Historians of England, vol. 4, pt. 2 (London: Seeley, 1861). Online edition, ed. Scott McLetchie, 2009. Available from , accessed 14 March 2014.
2. Cognates of ‘mara’, which itself derives from the Indo-European word moros (to drive out) or mar (to crush) are found in many northern European languages.
3. Adler Shelley R. , Sleep Paralysis: Night-Mares, Nocebos, and the Mind–Body Connection (New Brunswick, NJ: Rutgers University Press, 2011), 14–16.
4. See especially the work conducted by Owen Davies, ‘The Nightmare Experience, Sleep Paralysis and Witchcraft Accusations’, Folklore, 2003,114, 181–203. The term ‘hag’ derives from the OE hægtesse, meaning ‘witch’.
5. See, amongst others, Paul Barber, Vampires, Burial, and Death (New Haven, CT: Yale University Press, 1988); Marie-Hélène Heut, ‘Deadly Fears: Dom Augustin Calmat's Vampires and the Rule over Death’, Eighteenth-Century Life, 1997, 21, 222–32; Koen Vermier, ‘Vampires as Creatures of the Imagination: Theories of Body, Soul, and Imagination in Early Modern Vampire Tracts (1659–1755)’, in Yvonne Maskell, ed., Diseases of the Imagination and Imaginary Disease in the Early Modern Period (Turnhout: Brepols, 2011), 341–73; Peter J. Bräunlein, ‘The Frightening Borderlands of Enlightenment: The Vampire Problem’, Studies in History and Philosophy of Biological and Biomedical Sciences, 2012, 43, 710–19.