@articleHemsel_Mracek_Twiefel_Vasiljev_2006, title=Piezoelectric linear motor concepts based on coupling of longitudinal vibrations, volume=44, Supplement, DOI=10.1016/j.ultras.2006.05.056, number=0, journal=Ultrasonics, author=Hemsel, Tobias and Mracek, Maik and Twiefel, Jens and Vasiljev, Piotr, year=2006, pages=e591–e596