Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsFactory for Frac-tiles of Order Fourhttp://demonstrations.wolfram.com/FactoryForFracTilesOfOrderFour/]]>http://demonstrations.wolfram.com/FactoryForFracTilesOfOrderFour/