Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsCompressibility Factors for van der Waals Gaseshttp://demonstrations.wolfram.com/CompressibilityFactorsForVanDerWaalsGases/]]>http://demonstrations.wolfram.com/CompressibilityFactorsForVanDerWaalsGases/