Preparation and properties of serum and plasma proteins. IV. A system for the separation into fractions of the protein and lipoprotein components of biological tissues and fluids - Cohn, E. J; Strong, L. E; Hughes, W. L, Jr.; Mulford, D. J; Ashworth, J. N; Melin, M; Taylor, H. L (J. Amer. chem. Soc, 1946)