Wongkaew, A., Saito, H., Chueasamat, A., Aramrak, S., Nakasathien, S., and Sreewongchai, T., “Small-scale spatial variability of selected soil properties in a sloped cultivation area  A case study of Phetchabun province’s highland region, Thailand”, Int. J. Agric. Tech., vol. 22, no. 2, pp. 1017–1044, Mar. 2026.