1. K. WASHINGTON, Ann. Bot. (London), 37 (1923) 629.
2. G. V. IYENGAR, W. E. KOLLMER, H. J. M. BOWEN, The Elemental Composition of Human Tissues and Body Fluids, Verlag Chemie, Weinheim, New York, 1978.
3. N. N. GREENWOOD, Boron: Chapter II: Comprehensive Inorganic Chemistry-Volume 1, Pergamon Press, Oxford, 1973, p. 693.
4. E. J. UNDERWOOD, Trace Elements in Human and Animal Nutrition, Academic Press, New York, 1977, p. 436.
5. P. J. TEMPLE, S. N. LINZON, J. Air Pollut. Control Assoc., 26 (1976) 499.