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Risum O, Abdelnoor M, Svennevig JL, Nitter-Hauge S, Levorstad K, Foerster A, Frøysaker T.Risum O, et al. Among authors: froysaker t.Cardiovasc Surg. 1995 Oct;3(5):537-44. doi: 10.1016/0967-2109(95)94455-6.Cardiovasc Surg. 1995.PMID: 8574540