Merrill RM, Kelley TA, Cox E, Layman AB, Layton BJ, Lindsay R. Factors and barriers influencing influenza vaccination among students at Brigham Young University. Med Sci Monit. 2010 Feb;16(2):PH29-34.
Urrutia I, Aguirre U, Sunyer J, Plana E, Muniozguren N, Martinez-Moratalla J. Changes in the prevalence of asthma in the Spanish cohort of the European Community Respiratory Health Survey (ECRHS-II). Arch. Bronconeumol. 2007 Aug;43(8):425-30.