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2. The United States Pharmacopoeia, 22nd Edn., United States Pharmacopoeial Convention, Inc, Rockville, 1990.
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4. The British Pharmacopoeia, I, Her Majesty’s Stationery Office, London, 1990.
5. G. Battormann, K. Cabrera, S. Heizenroeder, D. Lubda, Labor Praxis 30 (1998) 32.