@article{Neumann:2006,
  author  = "K. Neumann and S. Zontek",
  title   = "On geometry of the set of admissible quadratic estimators of quadratic functions of normal parameters",
  journal = "Discussiones Mathematicae : Probability and Statistics",
  volume  = "Vol. 26",
  number  = "no 2",
  pages   = "109--125",
  year    = "2006",
}