Randall K. Fish Mari Ostendorf Gary D. Bernard David A. Castañon Multilevel Classification of Milling Tool Wear with Confidence Estimation. 75-85 2003 25 IEEE Trans. Pattern Anal. Mach. Intell. 1 http://computer.org/tpami/tp2003/i0075abs.htm db/journals/pami/pami25.html#FishOBC03