Uncertain geometry with circles, spheres and conics
   author = 	 {C. Perwass and W. F{\"o}rstner},
  title = 	 {Uncertain Geometry with Circles, Spheres and Conics},
  booktitle = 	 {Geometric Properties from Incomplete Data},
  pages =	 {23-41},
  publisher =	 {Springer-Verlag},
  series =       {Computational Imaging and Vision},
  volume =       {31},
  year =	 2006,
  editor =	 {R. Klette and R. Kozera and L. Noakes and J. Weickert}
}