José María Martínez-Otzeta Basilio Sierra Elena Lazkano Ekaitza Jauregi Y. Yurramendi Analyzing Classifier Hierarchy Multiclassifier Learning. 775-782 2008 CIARP http://dx.doi.org/10.1007/978-3-540-85920-8_94 conf/ciarp/2008 db/conf/ciarp/ciarp2008.html#Martinez-OtzetaSLJY08