RPW Duin, M Loog, R Haeb-Umbach (2000), Multi-class Linear Feature Extraction by Nonlinear PCA., A Sanfeliu, JJ Villanueva, M Vanrell, R Alquezar, AK Jain, J Kittler (Eds.), In ICPR15, Proc. 15th Int. Conference on Pattern Recognition p.398-401.

M Loog (1999), Approximate pairwise accuracy criteria for multiclass linear dimension in reduction.