6Akridge, Jay, and Linda Whipker. Precision agricultural services dealership survey results [ J ]. Center for Agricultural Business, Purdue University, West Lafayette, IN. 2001.
7Berry J K, Beyond mapping: Concepts, algorithms, and issues in GIS[M]. GIS World Books, Ft. Collins, CO.1993.
8Eghball & Varvel. Fractal analysis of temporal yield variability of crop sequences: implications for site-specific management[J]. Agron J,1997,89:851-855.
9Engel T, Hoogenboom G, Jones J W, et al. AEGIS/WIN: A computer program for the application of crop simulation models across geographical areas[J]. Agron J,1997,89:919-928.
10Han S, Hummel J W. Goering C E, et al. Cell size selection for site-specific crop management [J], Trans ASAE, 1994,37:19- 26.
