An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Winsor JE, Butterworth J, Boone J.Winsor JE, et al. Among authors: butterworth j.Intellect Dev Disabil. 2011 Aug;49(4):274-84. doi: 10.1352/1934-9556-49.4.274.Intellect Dev Disabil. 2011.PMID: 21721980
Migliore A, Butterworth J, Nord D, Cox M, Gelb A.Migliore A, et al. Among authors: butterworth j.Intellect Dev Disabil. 2012 Jun;50(3):207-18. doi: 10.1352/1934-9556-50.3.207.Intellect Dev Disabil. 2012.PMID: 22731970