1. Department of Rheumatology, Basel University, Basel, Switzerland
2. Department of Rheumatology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
3. Department of Rheumatology and INSERM U1016, Descartes University, Cochin Hospital, Paris, France
4. Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
5. Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA
6. Department of Medicine, University of Michigan, University of Michigan Scleroderma Program, Ann Arbor, MI, USA