One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "etterment". Encyclopædia Britannica (به انگلیسی). Vol. 3 (11th ed.). Cambridge University Press. pp. 831–832.
books.google.com
Anthony Steuer, Questions and Answers on Life Insurance: The Life Insurance Toolbook, p. 310 (Anthony Steuer, 2007) found at Google Books. Accessed June 18, 2009.
EConned[پیوند مرده], by Yves Smith, 2010, Palgrave Macmillan, p 243, and entire chapter Heart of Darkness