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http://www.google.com/#hl=en&source=hp&q=+milestones+in+the+development+of+cognitive+psychology+&aq=f&aqi=g1g-m3&aql=&oq=&gs_rfai=CjhSRm7t-TJitKJmMhQSexZWkBQAAAKoEBU_Qxkfg&pbx=1&fp=e6c57a2ab5279010