@inproceedingsHemsel_Mracek_Wallaschek_Vasiljev_2004, title=A novel approach for high power ultrasonic linear motors, volume=2, DOI=10.1109/ULTSYM.2004.1417988, number=Vol.2, booktitle=Ultrasonics Symposium, 2004 IEEE, author=Hemsel, Tobias and Mracek, Maik and Wallaschek, Jörg and Vasiljev, Piotr, year=2004, pages=1161–1164 
LibreCat: /record/9519
DOI: 10.1109/ULTSYM.2004.1417988

@inproceedingsHemsel_Wallaschek_2000, title=State of the art and development trends of ultrasonic linear motors, volume=1, DOI=10.1109/ULTSYM.2000.922635, booktitle=Ultrasonics Symposium, 2000 IEEE, author=Hemsel, Tobias and Wallaschek, Jörg, year=2000, pages=663–666 vol.1 
LibreCat: /record/8915
DOI: 10.1109/ULTSYM.2000.922635