This code system http://terminology.hl7.org/CodeSystem/citation-classifier defines the following codes:

Code Display Definition
D000076942 Preprint Scientific manuscript made available prior to PEER REVIEW.
D019991 Database A structured file of information or a set of logically related data stored and retrieved using computer-based means.
D001877 Book Non-periodical written or printed works consisting of sheets of pages fastened or bound together within covers.
D064886 Dataset Works consisting of organized collections of data, which have been stored permanently in a formalized manner suitable for communication, interpretation, or processing.
68059040 Video-Audio Media Used with articles which include video files or clips, or for articles which are entirely video.
audio Audio file The article cited is an audio file.
image Image file The article cited is an audio file.
machine-code Machine code The article cited is machine code.
protocol Protocol The article cited is the protocol of an activity and not the results or findings.
FHIR-resource FHIR Resource The article cited is a FHIR resource.
<status value="draft"/><experimental value="false"/><date value="2020-12-28T16:55:11+11:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="Used for many classifiers including PublicationType, CitationSubset, MeshHeading, Chemical."/><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/citation-classifier"/><content value="complete"/><concept><code value="D000076942"/><display value="Preprint"/><definition value="Scientific manuscript made available prior to PEER REVIEW."/></concept><concept><code value="D019991"/><display value="Database"/><definition value="A structured file of information or a set of logically related data stored and retrieved using computer-based means."/></concept><concept><code value="D001877"/><display value="Book"/><definition value="Non-periodical written or printed works consisting of sheets of pages fastened or bound together within covers."/></concept><concept><code value="D064886"/><display value="Dataset"/><definition value="Works consisting of organized collections of data, which have been stored permanently in a formalized manner suitable for communication, interpretation, or processing."/></concept><concept><code value="68059040"/><display value="Video-Audio Media"/><definition value="Used with articles which include video files or clips, or for articles which are entirely video."/></concept><concept><code value="audio"/><display value="Audio file"/><definition value="The article cited is an audio file."/></concept><concept><code value="image"/><display value="Image file"/><definition value="The article cited is an audio file."/></concept><concept><code value="machine-code"/><display value="Machine code"/><definition value="The article cited is machine code."/></concept><concept><code value="protocol"/><display value="Protocol"/><definition value="The article cited is the protocol of an activity and not the results or findings."/></concept><concept><code value="FHIR-resource"/><display value="FHIR Resource"/><definition value="The article cited is a FHIR resource."/></concept></CodeSystem>