Heparin and dihydroergotamine prophylaxis against thromboembolism after hip arthroplasty - Kakkar, V V; Fok, P J; Murray, W J G; Paes, T; Merenstein, D; Dodds, R; Farrel, R; Crellin, R Q; Thomas, E M; Morley, T R; Price, A J (J Bone Joint Surg, 1985)