Unfractionated heparin inhibits thrombin-catalysed amplification reactions of coagulation more efficiently than those catalysed by factor Xa - Ofosu, EA; Hirsh, J; Esmon, Cl; Modi, GJ; Smith, LM; Anvari, N; Buchanan, MR; Fenton, JW; Blajchman, MA (Biochem J, 1989)