References
References
- Salmon G 1904 A Treatise on Conic Sections, Longmans & Green
- DeTemple , DW . 1984 . Geometric procedures for graphing the general quadratic equation . The College Mathematics Journal , 15 : 313
- Cederberg JN 1989 A Course in Modern Geometries, Springer
- Kimberling C 2003 Geometry in Action, Key College Publications