Tham khảo Cực và đường thẳng đối cực

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  • Coxeter HSM, Greitzer SL (1967). Geometry Revisited. Washington: MAA. tr. 132–136, 150. ISBN 978-0-88385-619-2. 
  • Dörrie, H. 100 Great Problems of Elementary Mathematics: Their History and Solutions. New York: Dover, p. 157, 1965.
  • Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA: Houghton Mifflin, pp. 100–106, 1929.
  • Johnson RA (1960). Advanced Euclidean Geometry: An Elementary treatise on the geometry of the Triangle and the Circle. New York: Dover Publications. tr. 100–105. 
  • Gray J J (2007). Worlds Out of Nothing: A Course in the history of Geometry in the 19th century. London: Springer Verlag. tr. 21. ISBN 978-1-84628-632-2. 
  • Korn GA, Korn TM (1961). Mathematical Handbook for Scientists and Engineers. New York: McGraw-Hill. tr. pp43–45. LCCN 59014456.  Bảo trì CS1: Văn bản dư (link) The paperback version published by Dover Publications has the ISBN 978-0-486-41147-7.
  • Wells D (1991). The Penguin Dictionary of Curious and Interesting Geometry. New York: Penguin Books. tr. 190–191. ISBN 0-14-011813-6.