1. Boron chemistry;Morgan,1980
2. Trace elements in soils;Aubert,1977
3. Geochemistry of micronutrients;Krauskopf,1972
4. The trace-element content of soils, 1955;Swaine,1955
5. Distribution of boron in the environment;Argust;Biol. Trace Elem. Res.,1998