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2. The early diagnosis of thromboembolism by ultrasound;Evans;Ann R Coll Surg Engl,1971
3. The clinical significance of venous thrombosis of the calf;Doouss;Br J Surg,1976
4. Efficacy of low dose heparin in preventing postoperative fatal pulmonary embolism: results of an international multicentre trial;Kakkar;Lancet,1975
5. Clinical factors and the risk of deep venous thrombosis;Nicolaides,1975