[
  {
    "type": "identifier_scheme",
    "key": "DOI",
    "text": "Digital object identifier (DOI)"
  },
  {
    "type": "identifier_scheme",
    "key": "URN",
    "text": "Uniform Resource Name (URN)"
  },
  {
    "type": "identifier_scheme",
    "key": "ISBN",
    "text": "International Standard Book Number (ISBN)"
  },
  {
    "type": "identifier_scheme",
    "key": "STANDARD_NUMBER",
    "text": "Standard Number"
  }
]
