Safitra, R.M., Heriawan, M.N., Anggayana, K., Rubiarto, R. and Lubis, I.A. 2024. Drill Hole Spacing Analysis for Evaluation of Quartz Sand Resources as Residual Material from On-Land Alluvial Tin Processing based on Global Estimation Variance and Kriging Variance, with Case Study in the Bangka and Belitung Islands, Indonesia. Journal of Engineering and Technological Sciences. 56, 5 (Sep. 2024), 652–665. DOI:https://doi.org/10.5614/j.eng.technol.sci.2024.56.5.9.