Simek, Rudolf (2007) translated by Angela Hall. Dictionary of Northern Mythology, pages 7-8 and 73—74. D.S. Brewer. ISBN 0-85991-513-1 (ing.)
Solopova, Elizabeth (2009), Languages, Myths and History: An Introduction to the Linguistic and Literary Background of J.R.R. Tolkien’s Fiction, New York City: North Landing Books, p. 26, ISBN 0-9816607-1-1 (ing.)
