Ni’mah, Y. L., Hernanda, R. A. and Suprapto, S. (2026) “Nickel Extraction from Kolaka Laterite Ore: A HCl Leaching Optimization Method Using the BBD-RSM and Recovery via Oxalate Precipitation”, Engineering, Technology & Applied Science Research. Greece, 16(1), pp. 31795–31801. doi: 10.48084/etasr.15251.