The American College of Rheumatology 1990 criteria for the classification of vasculitis. Patients and methods - Bloch, DA; Michel, BA; Hunder, GG; McShane, DJ; Arend, WP; Calabrese, LH; Edworthy, SM; Fauci, AS; Fries, JF; Leavitt, RY (Arthritis Rheum, 1990)