Nathan RA, Meltzer EO, Blaiss MS, Murphy KR, Doherty DE, Stoloff SW. Comparison of the Asthma in America and Asthma Insight and Management surveys: did asthma burden and care improve in the United States between 1998 and 2009? Allergy Asthma Proc. 2012 Jan-Feb; 33(1):65-76.