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This article may be downloaded for personal use only. Permission to reproduce this article must be sought from Springer. This is the author's accepted manuscript version of an article published in the Journal of Autism and Developmental Disorders, 39(10): 1369-1380, 2009. The final publication is available at www.springerlink.com
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Journal of Autism and Developmental Disorders, 39(10): 1369-1380