1. R. Cremlyn and S. W. Ahmad, Egypt. J. Chem. 28, 539 (1985).
2. R. F. Kaltenbach and G. L. Trainor, US Patent No. 6617310 (2003).
3. N. X. Ju, C. E. Raab, D. C. Lin, et al., J. Labelled Compd. Radiopharm. 47, 115 (2004).
4. A. C. Sartorelli and K. Chyam, US Patent No. 4684747 (1987).
5. Sharaf El-Din Nalaviya, Khim. Geterotsikl. Soedin., No. 4, 523 (2000).