How to reference PDF documents

Hi,
We have a case where we need structured data for publications. Each publication is a node on the website with a title, a short description, a date, an author and a link to the publication itself which is a PDF document. We could also imagine that we would have different types of documents (PDF, Word, Excel, etc.). What would be the way to reference such linked documents and what item type would best fit such a piece of content?
In my opinion, the Article type would fit our needs, but we should have a property such as “relatedDocument” (URL) and “relatedDocumentType” (Text) to allow for a distinction between the different file types. The related/linked document, in our case, is the core content of the node.
Regards,
Arnaud