1. Arnon D I 1949 Plant Physiol. 24, 1–15.
2. Clark R B 1982 J. Plant Nutr. 5, 251–268.
3. Epstein E and Jefferies R L 1964 Ann. Rev. Plant Physiol. 15, 169–184.
4. Heinz D J, Krishnamurthi M, Nickell L G and Maretzki A 1977 In Applied and Fundamental Aspects of Plant Cell Tissue and Organ Culture. Ed. J Reinert and Y P S Bajaj. Springer-Verlag, Berlin.
5. Maehyl A C 1954 Methods of Biochemical Analysis.Vol. 2. Interscience. pp 385–386.