1. J. C. Colin, J. F. Thorpe,Synthetic Dye Stuffs and Intermediate Products, 7th Ed., Griffin, London, 1933.
2. F. D. Snell, C. L. Hilton,Encyclopedia of Industrial Chemical Analysis, Vol. 5, Interscience, New York, 1967, p. 421.
3. S. Coffey (ed.),Rodd's Chemistry of Carbon Compounds, 2nd Ed., Vol. III, Aromatic Compounds, Part C, Elsevier, Amsterdam, 1973
4. Indian Standard 5299, 1969.
5. Indian Standard 4334, 1967.