Syafriadi, S., Adriana, R. and Riyanto, A. 2023. Effect of Concentration Variation of Cacao Leaf Extract (Theobroma cacao.) Inhibitor on the Corrosion Rate of ST 37 Steel in 3% HCl Solution. Journal of Energy, Material, and Instrumentation Technology. 4, 1 (Feb. 2023), 1–9. DOI:https://doi.org/10.23960/jemit.v4i1.35.