1. N. S. Poonia and W. R. Truter, J. Chem. Soc. Dalton Trans., 16 (1972) 1791.
2. W. Prodinger, Organic Reagents Used in Quantitative Inorganic Analysis, p. 31, Elsevier, New York 1940.
3. T. N. Srivastova and G. Hohan, Indian J. Appl. Chem., 33 (1970) 314.
4. D. J. Ryabthikov and E. K. Golbraigh, The Analytical Chemistry of Thorium, p. 56, Pergamon Press, London 1963.
5. I. Rayce, Polish J. Chem., 55 (1981) 775.