Ilyasov, A. M., and Zhamanbalin М. B. “Features of the Production and Calibration of Reference Hardness Test Blocks: Features of the Production and Calibration of Reference Hardness Test Blocks”. Physical Sciences and Technology, vol. 9, no. 3-4, Oct. 2022, pp. 32-38, doi:10.26577/phst.2022.v9.i2.05.