Ellipses
Sources
Sources used in this book: CliffsNotes.com. Ellipse. 27 Jul 2010
Holt, Rinehart & Winston , "Conic Sections ." http://my.hrw.com/math06_07/nsmedia/homework_help/alg2/alg2_ch10_03_ homeworkhelp.html (accessed 7/27/2010).
Kenny Felder, "Conic Concepts -- Circles," Connexions, March 22, 2010, http://cnx.org/content/m18245/1.3/.