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Klein AL, Tajik AJ.Klein AL, et al. Among authors: tajik aj.J Am Soc Echocardiogr. 1991 Jul-Aug;4(4):379-92. doi: 10.1016/s0894-7317(14)80448-3.J Am Soc Echocardiogr. 1991.PMID: 1910836Review.