Quy Giang, Pham, Kanchana Nakhapakorn, and Achara Ussawarujikulchai. 2017. “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 9 (1). Nakhon Pathom, Thailand:31-37. https://ph02.tci-thaijo.org/index.php/ennrj/article/view/82460.