Popper, K. R. "Of Clouds and Clocks," in his Objective Knowledge, corrected edition, pp. 206–55, Oxford, Oxford University Press (1973), p. 231 footnote 43, & p. 252; also Popper, K. R. "Natural Selection and the Emergence of Mind", 1977.
David Miller. Fs1.law.keio.ac.jp (17 September 1994). ციტირების თარიღი: 21 December 2012.
london-gazette.co.uk
London Gazette (5 March 1965). დაარქივებულია ორიგინალიდან — 28 მაისი 2013. ციტირების თარიღი: 1 December 2012.
London Gazette (12 June 1982). დაარქივებულია ორიგინალიდან — 28 მაისი 2013. ციტირების თარიღი: 1 December 2012.
nytimes.com
„Sir Karl Popper Is Dead at 92. Philosopher of 'Open Society'“. The New York Times. 18 September 1994. ციტირების თარიღი: 15 November 2012. ციტატა: „Sir Karl Popper, a philosopher who was a defender of democratic systems of government, died today in a hospital here. He was 92. He died of complications of cancer, pneumonia and kidney failure, said a manager at the hospital in this London suburb.“
