Wahjono, H.B. and 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 (Dec. 2021), 46–54. DOI:https://doi.org/10.37367/jpi.v5i2.158.