F3 and hemorrhagic disease: In particular, we identified a plausible value for the constant of the reaction describing the autoactivation of factor XII (since no reference values can be found in literature); moreover, the results of the PSA over factor IX suggest that a deficiency of this factor is not enough to cause severe bleeding disorders as haemophilia B, but an alteration of other factors seems to be necessary for the occurrence of such condition (e.g., the lack of Tissue Factor, as suggested by the PSA-2D over Tissue Factor and factor IX).