2) The International Study of Asthma and Allergies in Childhood (ISAAC) Steering Committee. Worldwide variation in the prevalence of asthma symptoms: the International Study of Asthma and Allergies in Childhood (ISAAC). 1998; Eur respir J 12: 315-335.
3) Williams, H., Robertson, C., Stewart, A., et al. Worldwide variations in the prevalence of symptoms of atopic eczema in the International Study of Asthma and Allergies in Childhood. J Allergy Clin Immunol 1999; 103: 125-138.
4) Strachan, D. P., Sibbald, B., Weiland, S. K., et al. Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC). Pediatr Allergy Immunol 1997; 8: 161-176.