Measurement of low molecular weight heparin ex vivo activities in clinical laboratories using variousanti Xa assays: interlaboratory variability and requirement of an agreed low molecular weight heparin standard - Sie, P; Aillaud, MF; de Prost, D; Droulle, C; Forestier, F; Guedj, P; Juhan-Vague, I; Polack, B; Potron, G; Roncato, M; Roussi, J; Sampol, J; Aiach, M (Thromb Haemost, 1987)