1. Goovaerts, P. 1997. Geostatistics for Natural Resources Evaluation. Oxford University Press, New York.
2. Inthavong, T. 2009. Spatial variation in water availability, soil nutrient and water constraints for rainfed lowland rice production in Savannakhet province, southern Lao PDR. PhD Thesis, University of Queensland, Brisbane.
3. SSLCC. 1996. Soil physical and chemical properties analysis for Soil of Lao PDR. Soil Survey and Land Classification Center (SSLCC), Vientiane.