References
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- Bould, C., Aduayi, E. A. and Kimeu, B. S. (1971). A Leaf Analysis Service for Coffee Growers. Kenya Coffee 2, 37–39.
- Cooke, P. (1969). Atomic Absorption Spectrophotometry (published by Pye Unicam Ltd.).
- O'Neill J. V. and Webb, R. A. (1970). Simultaneous Determination of Nitrogen, Phosphorus and Potassium in Plant Material by Automatic Methods. J. Sci. Fd. Agric. 5, Vol. 21, 217–219.
- Varley, J. A. (1960). Automatic Methods for the Determination of Nitrogen, Phosphorus and Potassium in Plant Material. Analyst, Lond. 91, 119.