Contributions to the optimal use of human blood II. The large-scale preparation of prothrombin complex. A comparison between two methods using the anion exchangers DEAE-Cellulose DE 52 and DEAE-Sephadex A-50 - Heystek, J; Brummelhuis, H. G. J; Krijnen, H. W (Vox Sanguinis, 1973)