Eular recommendations for conducting clinical studies and/or clinical trials in systemic vasculitis: Focus on anti-neutrophil cytoplasm antibody-associated vasculitis - Hellmich, B; Flossmann, O; Gross, W L; Bacon, P; Cohen-Tervaert, J W; Guillevin, L; Jayne, D; Mahr, A; Merkel, P A; Raspe, H; Scott, D G; Witter, J; Yazici, H; Luqmani, R A (Ann Rheum Dis, 2007)