9SCHAEFER N L. Evaluation of a hand held reflectometer for rapid quantitative determination of nitrate[J]. Communications in Soil Science and Plant Analysis, 1986, 17(17): 937-951.
10ROTI-I G W, FOX R H, FOX R H, et al. Development of a quick test kit method to measure soil nitrate[J]. Communications in Soil Science and Plant Analysis, 1991, 22(3): 191-200.