Supercritical CO2-assisted methods for the production and pulmonary administration of pharmaceutical aerosols Journal of Aerosol Science, Volume 29, Supplement 2, September 1998, Pages S1271-S1272 R. E. Sievers, P. D. Milewski, S. P. Sellers, K. D. Kusek, P. G. Kleutz, B. A. Miles