N. Brawira, H. Nurdin, R. Lapisa, and B. Syahri, “Analysis of Hardness on the Tapping Knife of Rubber Plants Made of Medium Carbon Steel Resulting from Quenching Process with Different Cooling Mediums”, INVOTEK: Jurnal Inovasi Vokasional dan Teknologi, vol. 22, no. 2, pp. 91-96, Jul. 2022.