BABU K, VINEETH FRANCIS, S. P. S. L. P. M. S. P. T. F. Virtual Keyboard. International Journal of Engineering and Computer Science, india, v. 6, n. 3, 2017. Disponível em: http://ijecs.in/index.php/ijecs/article/view/3482. Acesso em: 7 may. 2024.