1. Guidelines for assuring the quality of pharmaceutical and biological products prepared by recombinant DNA technology. In: WHO Expert Committee on Biological Standardization. Forty-first report. Geneva, World Health Organization, 1991, Annex 3 (WHO Technical Report Series No. 814).
2. Requirements for the use of animal cells as in vitro substrates for the production of biologicals. In: WHO Expert Committee on Biological Standardization. Forty-seventh report. Geneva, World Health Organization, 1998, Annex 1 (WHO technical report series no. 878).
3. WHO reference materials for cytokines/growth factors and endocrinological substances (available on the internet at http://www.who.int/bloodproducts/Catalogue/en/index.html).
4. 12th international conference of drug regulatory authorities recommendation (available on the internet at http://www.who.int/medicines/areas/quality_safety/regulation_legislation/icdra/recc_final.pdf).
5. WHO Expert Committee on Biological Standardization. Fifty-sixth report. Geneva, World Health Organization (WHO technical report series no. 941), in press.