Mracek, Maik, et al. “Driving Concepts for Bundled Ultrasonic Linear Motors.”10.1007/s10832-007-9123-5__Journal of Electroceramics, vol. 20, no. 3–4, Springer US, 2008, pp. 153–58, doi:10.1007/s10832-007-9123-5.

Mracek, Maik, and Tobias Hemsel. “Synergetic Driving Concepts for Bundled Miniature Ultrasonic Linear Motors.”10.1016/j.ultras.2006.05.201__Ultrasonics, vol. 44, Supplement, 2006, pp. e597–602, doi:10.1016/j.ultras.2006.05.201.

Hemsel, Tobias, and Jörg Wallaschek. “State of the Art and Development Trends of Ultrasonic Linear Motors.”10.1109/ULTSYM.2000.922635__Ultrasonics Symposium, 2000 IEEE, vol. 1, 2000, pp. 663–66 vol.1, doi:10.1109/ULTSYM.2000.922635.