1. Department of Dermatology; University of Groningen, University Medical Centre Groningen; Groningen The Netherlands
2. Department of Medical Informatics, Biometry and Epidemiology; Friedrich-Alexander-University Erlangen/Nürnberg; Erlangen Germany
3. Department of Dermatology; Medical University of Graz; Graz Austria
4. Department of Dermatology; University Hospital of Puerto Real, University of Cádiz; Cádiz Spain
5. Department of Dermatology; University Hospital Zürich and Clinic of Dermatology and Allergology, Kantonsspital St Gallen; Zürich Switzerland
6. Department of Dermatology; University Hospital Carl Gustav Carus, University Allergy Centre, Technical University Dresden; Dresden Germany
7. Department of Dermatology; Poznan University of Medical Sciences; Poznan Poland
8. Department of Dermatology; University Hospital Jena; Jena Germany
9. Department of Dermatology, University Hospital Complex; Faculty of Medicine, A Coruña, Santiago de Compostela; also: Dermatological Office; Vigo Spain
10. Department of Dermatology; Hospital del Mar, IMIM Universitat Autònoma; Barcelona Spain
11. Department of Dermatology and Environmental Medicine; Institute for Interdisciplinary Dermatologic Prevention and Rehabilitation (iDerm), Lower Saxony Institute for Occupational Dermatology (NIB), University of Osnabrück; Osnabrück Germany
12. Faculty of Medicine and Health Science; The Jan Kochanowski University; Kielce Poland
13. Department of Dermatology; University of Erlangen/Nürnberg; Erlangen Bavaria
14. Division of Allergology; Paul-Ehrlich-Institut; Langen Germany
15. Department of Dermatology and Allergology; Amsterdam University Medical Centers; Amsterdam The Netherlands
16. Department of Dermatology; University Hospital de la Princesa; Madrid Spain
17. Department of Dermatology, Inselspital; Bern University Hospital, University of Bern; Bern Switzerland
18. Department of Skin and Venereal Diseases; Lithuanian University of Health Sciences; Kaunas Lithuania
19. Department of Clinical Social Medicine, Environmental and Occupational Dermatology; University of Heidelberg; Heidelberg Germany