Synergistic effect of low doses of tumor necrosis factor and sera from patients with systemic lupus erythematosus on the expression of procoagulant activity by cultured endothelial cells - Hasselaar, P; Derksen, RHWM; Oosting, JD; Blokzijl, L; de Groot, PG (Thromb Haemost, 1989)