Hooker, Richard (1597). Of the Laws of Ecclesiastical Polity. I.xi. as quoted in Kirk, Kenneth E. (1920). Some Principles of Moral Theology. London, England: Longmans, Green and Co. Ltd. p. 42, note 6. This article incorporates text from this source, which is in the public domain.
One or more of the preceding sentences incorporates text from a publication now in the public domain: Waldron, M.A. (1912). "Virtue". In Herbermann, Charles (ed.). Catholic Encyclopedia. New York: Robert Appleton Company.