1. ASTM, 2000. Standard practice for classification of soils for engineering purposes (Unified Soil Classification System). ASTM D2487. 2000 Annual Book of ASTM Standards. ASTM International, West Conshohocken, PA.
2. Benson, C.H., Gribb, M.M., 1997. Measuring unsaturated hydraulic conductivity in the laboratory and field. Unsaturated soil engineering practice. Geotechnical Special Publication. 68, Logan, Utah, 113–168.
3. Bodman, G.B., Colman, E.A., 1943. Moisture and energy conditions during downward entry of water into soils. Soil Sci. Soc. Am. Proc. 8, 116-122.
4. Brooks, R.H., Corey, A.T., 1964. Hydraulic Properties of Porous Media. Hydrology Paper No. 3, Colorado State University, Fort Collins, CO.
5. Bruce, R.R., Klute, A., 1956. The measurement of soil moisture diffusivity, Soil Sci. Soc. Am. Proc. 20: 458-462.