1. Respiratory Epidemiology, Occupational Medicine, and Public Health Group; National Heart and Lung Institute; Imperial College London; London UK
2. Department of Medical Sciences ‘M Aresu’; University of Cagliari; Cagliari Italy
3. Faculty of Medicine; University of Porto and Hospital São João; Porto Portugal
4. CINTESIS - Center for Health Technology and Services Research; Faculty of Medicine; University of Porto; Porto Portugal
5. Department of Internal Medicine; Lung Function Unit; Sapienza University of Rome; Rome Italy
6. Central Library; Imperial College London; London UK
7. Department of Medicine and Allergology; University of Oslo; Oslo Norway
8. Skin and Allergy Hospital; Helsinki University Central Hospital; Helsinki Finland
9. Second University of Naples and IFT-CNR; Rome Italy
10. Transylvania University Brasov; Brasov Romania
11. Centre for Paediatrics and Child Health; Institute of Human Development; The University of Manchester; Manchester UK