CHEN, Lian; WANG, Yuchen. Methods and Instruments for Measuring Rock Hardness. International Journal of Mechanical and Electrical Engineering, London, U.K., v. 7, n. 3, p. 21–33, 2025. DOI: 10.62051/ijmee.v7n3.04. Disponível em: https://wepub.org/index.php/IJMEE/article/view/5861. Acesso em: 24 may. 2026.