1. Mashkovsky, M. D. (2005) Drugs: Handbook for Physicians [in Russian], Novaya Volna, Moscow, pp. 579–580.
2. Numazawa, M., and Nagaoka, M. (1983) A facile synthesis of deoxycorticosterone using the controlled alkaline hydrolysis of 21-bromo-20-ketopregnenes, J. Chem. Soc. Chem. Commun., 3, 127–128.
3. El-Kady, I. A. (1982) 6b-Hydroxylation of steroids by extracts of Aspergillus niger, J. Gen. Microbiol., 128, 2511–2514.
4. Fouad, W. A., Abbas, I. H., Elwan, K. M., Swellum, M. A., and El-Dougdoug, Kh. A. (2009) Biotransformation of progesterone by microbial steroids, J. Appl. Sci. Res., 35, 137–143.
5. Metwali, M. R. (2002) Microbiological transformation of progesterone to 21-hydroxyprogesterone by Aspergillus niger (isolate No. 11/3), Bulletin of the Faculty of Science, Assiut University, D Botany, 31, 313–318.