Baba, I., 1955: Studies on the nutrition of the rice plant with special reference to nitrogen and silica. I. Translocation of absorbed silica in plant and its accumulation in the epidermal cells of leaf blade in relation to transpiration. Jpn. J. Crop Sci., 24, 29-33.
Eaton, A. D., Clesceri, L. S., and Greenberg, A. E., 1995: Standard methods for the examination of water and wastewater, 19th Edition. American Public Health Assn. Washington, DC.