An Extension of the Van der Waals Equation of State
  We extend the Van der Waals equation of state to a universal form and find that the van der Waals equation of state is a special condition of this form. Then a good form of the equation of state for a balanced liquid-gas coexistence canonical argon-like system is given. The localization of this universal form concludes the paper. 
Jianxiang Tian, Yuanxing Gui