1. Hayward, P. M. (1984). Determination of phytochrome para-meters from radiation measurements. In:Techniques in photo-morphogenesis. (Smith, H. and Holmes, M. G., Eds.). Academic Press, London, 159–73.
2. Hewitt, E. J. and Smith, T. A. (1975).Plant mineral nutrition. Fletcher and Sons Ltd. Norwich, UK.