AL-HELFAWI, M. The Percusioscope SPS. American Scientific Research Journal for Engineering, Technology, and Sciences, [S. l.], v. 49, n. 1, p. 40–50, 2018. Disponível em: https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/4465. Acesso em: 6 may. 2024.