Orgaran (Org 10172) or heparin for preventing venous thrombosis after elective surgery for malignant disease? A double-blind, randomised, multicenter comparison - Gallus, A; Cade, J; Ockelford, P; Hepburn, S; Maas, M; Magnani, H; Bucknall, T; Stevens, J; Porteous, F (Thromb Haemostas, 1993)