2Lark R M.Kriging a soil variable with a simple nonstation- ary variance model[Jl.Agric.Biol. Environ.Star,2009,14(3):301-321.
3Oliver M A.Richard Webster.A tutorial gqiide to geostatisti- es Computing and modelling vario -grams and kriging Review [J]. Catena, 2014 (113) : 56-59.
4Li Hongyi,Richard Webster,Shi Zhou.Mapping soil salinity in the Yangtze delta: REML and universal kriginited [J].Geoder- ma, 2015(237-238) : 71-77.