@article{vicsek1980simple,
  title={Simple variational method for the closures of the Ornstein-Zernike equation: A study of liquid instability},
  author={Vicsek, T},
  journal={Physica A: Statistical Mechanics and its Applications},
  volume={102},
  number={3},
  pages={523--531},
  year={1980},
  publisher={North-Holland}
}