Bing found the following results
Ellipse by LegXercise
Ellipse - Wikipedia
Ellipse - Equation, Formula, Properties, Graphing - Cuemath
Ellipse - Math is Fun
Intro to ellipses (video) | Conic sections | Khan Academy
Ellipse | Definition, Properties & Equations | Britannica
Ellipse (Definition, Equation, Properties, Eccentricity, Formulas)
Ellipse equation review (article) | Khan Academy
Ellipse - Math.net
Ellipse | Brilliant Math & Science Wiki