Low molecular weight heparin started before surgery as prophylaxis against deep vein thrombosis: 2500 versus 5000 Xal units in 2070 patients - Bergqvist, D; Burmark, U S; Flordal, P A; Frisell, J; Hallbook, T; Hedberg, M; Horn, A; Kelty, E; Kvitting, P; Lindhagen, A; Ljungstrom, K G; Matzsch, T; Risberg, B; Syk, I; Torngren, S; Wellander, E; Ortenwall, P (Br J Surg, 1995)