9."Motor technology dictionary", The Nikkan Kogyo Shinbun, Ltd., 2002.(in Japanese)    (Explanation of some technical terms about      digital control) 

10. Hiroshi Fujimoto, In "Motor technology practical handbook" (Edited by Daiki Ebihara, Yoichi Hori, and Hideo Doumeki), Chapter 2-       8: "Digital redesign", Chapter 2-10: "Perfect tracking control based on multirate sampling control",  The Nikkan Kogyo Shinbun,      Ltd., 2001.(in Japanese)