Wahjono, H. B., & Permana, A. C. (2021). Hardness Testing And Macro Photo Observation Automatic Surface Treatment Rail With Variation Of Heating Torch Distance And Cooling Nozzle. Jurnal Perkeretaapian Indonesia (Indonesian Railway Journal), 5(2), 46–54. https://doi.org/10.37367/jpi.v5i2.158