HAERTEL, Hermann. The Worldwide Simplest and Oldest Motor. European Journal of Physics Education, [S.l.], v. 11, n. 1, p. 37-46, jan. 2020. ISSN 1309-7202. Available at: <http://eu-journal.org/index.php/EJPE/article/view/257>. Date accessed: 29 feb. 2020.