http://mathworld.i2p/SixCirclesTheorem.html
See also Circle , Contact Triangle , Hexlet , Incircle , Nine Circles Theorem , Pappus Chain , Seven Circles Theorem References Bogomolny, A. " Six Circles Theorem (Evelyn). " http://www.cut-the-knot.org/Curriculum/Geometry/Evelyn.shtml . Bogomolny, A. " Six Circles Theorem (Elkies). " http://www.cut-the-knot.org/Curriculum/Geometry/Elkies.shtml .