Hechenbichler K. and Schliep K.P. (2004) Weighted k-Nearest-Neighbor Techniques and Ordinal Classification, Discussion Paper 399, SFB 386, Ludwig-Maximilians University Munich
(http://www.stat.uni-muenchen.de/sfb386/papers/dsp/paper399.ps)Hechenbichler K. (2005) Ensemble-Techniken und ordinale Klassifikation, PhD-thesis