A DOI (digital object identifier) is preceded by the text “doi:” (no capitalization and no space) in an AMA reference. Don’t present it in the form of a link; only include the DOI number itself. For example: “doi:10.1177/2373379916644449.”
AMA style states that you should include the DOI of a source whenever one is available. They mainly appear in AMA journal citations and can also appear in AMA book citations. When you include a DOI, don’t add a URL or access date.