Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsCross Sections of Quadratic Surfaceshttp://demonstrations.wolfram.com/CrossSectionsOfQuadraticSurfaces/]]>http://demonstrations.wolfram.com/CrossSectionsOfQuadraticSurfaces/