1. F. Feigl, Translated by R. E. Oesper, Spot Tests in Inorganic Analysis. Amsterdam: Elsevier. 1972. pp. 188, 191, 192.
2. l. c. 1, p. 359?361.
3. l. c. 1, pp. 175, 193, 301, 507.
4. K. Sriramam, Talanta22, 105 (1975).
5. F. G. Mann and B. C. Saunders, Practical Organic Chemistry. London: Longmans. 1960. p. 301.