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Symon DN, Stewart L, Russell G.Symon DN, et al.J Ment Defic Res. 1985 Sep;29 ( Pt 3):257-61. doi: 10.1111/j.1365-2788.1985.tb00336.x.J Ment Defic Res. 1985.PMID: 2933525
Symon DN, Russell G, Couzin DA, Stewart L.Symon DN, et al.Lancet. 1984 May 12;1(8385):1070. doi: 10.1016/s0140-6736(84)91472-7.Lancet. 1984.PMID: 6143993No abstract available.