1. Advisory Committee on Dangerous Pathogens (1995) Categorisation of biological agents according to hazard categories of containment, 4th edn, HSE Books, Sudbury, UK.
2. The Rules Governing Medicinal Products in the European Community (1992) Volume TV: Good Manufacturing Practice for Medicinal Products. Office of Publications of the European Community, Luxemburg.
3. US Food and Drug Administration (1992) Code of Federal Regulations: Parts 210/ 211: Current Good Manufacturing Practice Regulations, FDA, Bethesda.
4. BSI (1989) Environmental cleanliness in enclosed spaces, BS 5295, British Stand ards Institute, London.
5. US Federal Standard 209E (1992) Airborne Particulate Cleanliness in Cleanrooms and Clean Zones. Institute of Environmental Sciences, Mount Prospect, Illinois.