6World Health Organization.Guidelines for Drinking-Water Quali-ty[S].2nd ed.Recommendations.Geneva:WHO,1993.
7Prosun B,Gunnar J.High fluoride contents in groundwater in In-dia,IRD current issues,International Rural Development[R].Ultuna:Swedish University of Agricultural Sciences,1996.
8Shen Z L,Zhou M,Tang M G.The characteristicsof fluorine ingroundwater of North China and the significance of fluorite-waterinteraction to fluorine transportation[M] //Balkema A A.Pro-ceedings of the 6th International Symposium.Malvern:The 6thInternational Symposium,1989:93-97.
