Hisashi Kashima Kazutaka Yamasaki Akihiro Inokuchi Hiroto Saigo Regression with interval output values. 1-4 2008 ICPR http://dx.doi.org/10.1109/ICPR.2008.4761270 conf/icpr/2008 db/conf/icpr/icpr2008.html#KashimaYIS08