1. Freudenberg, K. and Weinges, K.Tetrahedron, 1960,8, 336.
2. Hergert, H. L. ..The Chemistry of Flavonoid Compounds, Ed. T. A. Geissman, Pergamon Press, 1962, p. 577.
3. Krishnamurthy, H. G., Krishnamoorthy, V. and Seshadri, T. R.Phytochemistry, 1963,2, 47.
4. Goel, R. N. and Seshadri, T. R.Tetrahedron, 1959,5, 91.
5. Freudenberg, K...Chemistry of Natural and Synthetic Colouring Matters and Related Fields, Ed. T. S. Gore, B. S. Joshi, S. V. Sunthankar and B. D. Tilak, Academic Press (New York), 1962, p. 224.