1. Department of Dermatology LangeLand Hospital Zoetermeer the Netherlands
2. Department of Dermatology Ghent University Hospital Ghent Belgium
3. Department of Dermatology Brigham and Women's Hospital, Harvard Medical School Boston Massachusetts USA
4. Harvard Medical School Boston Massachusetts USA
5. Countway Library of Medicine Harvard University Boston Massachusetts USA
6. Department of Dermatology Keck School of Medicine of University of Southern California Los Angeles California USA
7. National Psoriasis Foundation Portland Oregon USA
8. Department of Dermatology University of California San Francisco California USA
9. Department of Medicine, Division of Rheumatology Brigham and Women's Hospital, Harvard Medical School Boston Massachusetts USA