@incollection{Constantini-shape-preserving-2004,
  mrnumber = {MR2151355 (2006e:65013)},
  author = {Costantini, P. and Pelosi, F.},
  mrclass = {65D10 (41A15 65D07)},
  series = {Mod. Methods Math.},
  booktitle = {Mathematical methods for curves and surfaces: Troms\o\ 2004},
  title = {Shape preserving data approximation using new spline spaces},
  publisher = {Nashboro Press, Brentwood, TN},
  pages = {81--92},
  year = {2005},
}