Schmitt CL, Allen JA, Kosa KM, Curry LE. Support for a ban on tobacco powerwalls and other point-of-sale displays: findings from focus groups. Health Educ Res. 2015 Feb;30(1):98-106. doi: 10.1093/her/cyu046.
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.