In addition to the contributor association - in order to publish some datasets - it is also required to reference different type of contributors such as Projects or Funders. Type of contributor could be stated as a controlled vocabulary (Project, Funder, Sponsor, Researcher, etc.), please see e.g. contributorType in the DataCite Metadata Schema. Some important metadata references in research context are OpenAIRE, DataCite and
re3data.org Registry of Research Data Repositories which may function as sources for additional classes and properties.
This issues has been reported by Pirjo-Leena Forsström: