References
- E.H. Askwith, A Course of Pure Geometry Containing Complete Treatment of the Properties of Conic Sections, Cambridge University Press, Cambridge, 1917.
- E.H. Askwith, The Analytical Geometry of the Conic Sections, 3rd ed., Adam and Charles Black, London, 1938.
- S.L. Loney, The Elements of Coordinate Geometry, S. Chand, New Delhi, India, 1992.
- R.A. Johnson, Advanced Euclidean Geometry, Dover, New York, 2007.
- V.K. Srinivasan, The characterizations of triangles using their nine-point circles, Int. J. Math. Educ. Sci. Technol., DOI: 10.1080/0020739X.2011.644334.