K.-C. Bergmann, L. Lindemann, and G. Steinkamp, “Salmeterol/fluticasone propionate (50/250 µg) combination is superior to double dose fluticasone (500 µg) for the treatment of symptomatic moderate asthma”, Swiss Med Wkly, vol. 134, no. 0304, pp. 50–58, Jan. 2004.