1. Ultrasonic stepping motor using spatially shifted Standing vibrations;Nakamura;IEEE Trans. UFFC,1997
2. Ultrasonic Motors: Theory and Application;Ueha,1993
3. Hata, Y. and Okamoto, Y., Linear actuator. US Patent, Pub. No. US 2003/0222538; 2003, pp. 10–12.
4. Piezoelectric actuators driven by the saw-tooth-like motion of a stator;Takehiro;Elsevier Ultrason.,1996
5. Characteristics of a miniaturized ultrasonic motor for auto-focusing of a mobile phone;Lim;KIEE, J. Electric. Eng. Technol.,2006