1. British Pharmacopoeia, 1980, p. 665.
2. U.S. Pharmacopoeia, 21st ed., 1985, p. 947.
3. European Pharmacopoeia, 2nd ed. Part II–3, Council of Europe, 1981.
4. M. M. TUCKERMAN, L. C. BATE, G. W. LEDDICOTE, J. Pharm. Sci., 53 (1964) 983.
5. O. JOHANSEN, G. LUNDE, E. STEINNES, Kjeller Report KR-91. Institutt for Atomenergi, Kjeller, Norway, 1965.