@InProceedings{SchVig02,
  author    = {M.~Scholz and R.~{Vig\'{a}rio}},
  title     = {Nonlinear {PCA}: a new hierarchical approach},
  booktitle = {Proceedings ESANN},
  editor    = {M.~Verleysen},
  pages     = {439--444} ,
  year      = {2002},
}