Quy Giang, P., K. Nakhapakorn, and A. Ussawarujikulchai. “Effectiveness of different spatial interpolators in estimating heavy metal contamination in shallow groundwater: a case study of arsenic contamination in Hanoi, Vietnam”. Environment and Natural Resources Journal, vol. 9, no. 1, Apr. 2017, pp. 31-37, https://ph02.tci-thaijo.org/index.php/ennrj/article/view/82460.