Herman, Kevin, and Judi Prajetno Sugiono. “Studi Pengukuran Kekerasan Benda Dengan Analisa Spektral”. Journal of Informatics Development 1, no. 2 (April 30, 2023): 65–74. Accessed October 19, 2025. http://178.128.120.64/index.php/jid/article/view/1091.