1. Mengel , K. and
Kirkby , E.A. 1979. Principles of Plant Nutrition, 2nd Edition, 548–552. Switzerland: Int. Potash Institute Berne.
2. Vogel , A.I. 1955. A Textbook of Quantitative Inorganic Analysis, 502–504. London: Longmans, Green and Co.
3. Jackson , M.L. 1958. Soil Chemical Analysis, 294–296. Englewood Cliffs, N.J.: Prentice‐Hall, Inc.
4. A rapid determination of silicon in plant material