1. The United States Pharmacopeia Convention , The United States Pharmacopeia , ch. 231: heavy metals, in Revision Bulletin, Official April 1, 2015
2. The United States Pharmacopeia Convention , The United States Pharmacopeia , ch. 232: elemental impurities – limits, published in USP 40–NF 35, First Supplement, Official December 1, 2017
3. The United States Pharmacopeia Convention , The United States Pharmacopeia , chapter 233: elemental impurities – procedures, published in USP 38–NF 33, Second Supplement, Official December 1, 2015
4. Impact and practicability of recently introduced requirements on elemental impurities
5. Evaluation of dilute-and-shoot procedure for determination of inorganic impurities in liquid pharmaceutical samples by ICP OES