1. Bell, J., 1994. Dry powder inhalation technology, Pharmaceutical Manufacturing International, P.A. Barnacal, Sterling, London.
2. Dry powder aerosols I: a new powder inhalation device;Bell;J. Pharm. Sci.,1971
3. Box, G.P., Hunter, W.G., Hunter, J.S., 1978. Statistics for Experimenters, Wiley, New York.
4. The characterisation of inhalation devices by an inhalation simulator: the Electronic Lung™;Brindley;J. Aerosol. Med.,1994
5. British Pharmacopeia, 1993. Her Majesty's Stationary Office, London, Appendix XVII-C.