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Submitted on: 06 December 2010.
Revised on: 29 December 2010.
Accepted on: 08 January 2011.
Research in Developmental Disabilities
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Submitted on: 25 December 2008.
Revised on: 26 January 2009.
Accepted on: 05 February 2009.
Research in Developmental Disabilities
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Submitted on: 18 June 2000.
Revised on: 19 July 2000.
Accepted on: 07 August 2000.
Research in Developmental Disabilities