A comparative randomized trial of heparin versus streptokinase in the treatment of acute proximal venous thrombosis: an interim report of a prospective trial - Elliot, M; Immelman, P; Jeffery, P; Benatar, R; Funston, M; Smith, B; Shepstone, J; Ferguson, D; Jacobs, P; Walker, W; Louw, J (Br J Surg, 1979)