1. Pharmacopoeia of the United States, Vol. XVII, pp. 900–02, US Pharmacopoeial Convention, New York, USA (1965).
2. ”Method of grading glass for alkalinity,” IS Specification No. 2303–1963, Indian Standards Institution, New Delhi.
3. British Pharmacopoeia, p. 1366, General Medical Council, The Pharmaceutical Press, London (1968).