Efficacy and safety of low molecular weight heparin (ardeparin sodium) compared to warfarin for the prevention of venous thromboembolism after total knee replacement surgery: a double-blind, dose-ranging study - Heit, JA; Berkowitz, SD; Bona, R; Cabanas, V; Corson, JD; Elliott, CG; Lyons, R; (Ardeparin Arthroplasty Study Group) (Thromb Haemost, 1997)