Efficacy and safety of enoxaparin versus unfractionated heparin for prevention of deep venous thrombosis after elective knee arthroplasty. Enoxaparin Clinical Trial Group - Colwell,C.W.; Spiro,T.E.; Trowbridge,A.A.; Stephens,J.W.; Gardiner,G.A.; Ritter,M.A. (Clin Orthop, 1995)