IETF RFC 4627 http://www.ietf.org/rfc/rfc4627.txt (Normative JSON definition)
JSON. http://www.json.org/ (Informative)
Wikipedia, definition of JSON. http://en.wikipedia.org/wiki/JSON (Informative)
JSON in FHIR. http://www.hl7.org/implement/standards/fhir/formats.htm#json (Informative)