1. Gasparikova, O. (1992). Root metabolism. In:Physiology of the plant root system.Development in Plant and Soil Sciences. (Kolek, J. and Kozinka, V., Eds). 46, Kluwer Academic Publishers, London, 82–127.
2. Gill, A. M. and Tomlinson, P. B. (1975). Aerial roots: an array of forms and functions. In:The development and function of roots.(Torrey, J. and Clarkson, D., Eds). Academic Press, London, 237–60.
3. Tay, K. S. (1989)Study on gravitropic responses in the aerial rootsof ArachnisMaggie Oei.Thesis, The National University of Singapore.
4. Zar, J. H. (1984).Biostatistical analysis,Prentice Hall, Englewood Cliffs, NJ, USA.