4Gunsaulis.F.R,M.F Kocher,And C.L.Griffis.Surface struc-ture effects on close-range reflctance as a /unction of soil organic matter content[].Tranction of the ASAE.1991
5Baumgarder M F,Kristofs,Johannsen C J,et.Effects of Organic Matter on the Multispectral Properties of soil[].Proc A cadsci.1970