@article{Bojarski:1999,
  author  = "J. Bojarski and S. Gnot and E. Synówka",
  title   = "Nonnegative estimation of mean Squared errors of linear predictors in mixed linear models",
  journal = "Discussiones Mathematicae : Algebra and Stochastic Methods",
  volume  = "Vol. 19",
  number  = "no 2",
  pages   = "273--286",
  year    = "1999",
}