@Article{KruizingaPetkovIEEE-TIP2002,
  author =   {P. Kruizinga and N. Petkov},
  title =    {Non-linear operator for oriented texture},
  journal =  {IEEE Trans. on Image Processing},
  year =     {1999},
  volume =   {8},
  number =   {10},
  pages =    {1395-1407}
}