Linked Data: how link to non-RDF resource providing background information

In an RDF file that describes a resource I would like to include a link to a HTML document that provides background information. The document is HTML, not RDF. I have the feeling that this should be made clear, probably with some kind of format specification (like dcterms:format).

My questions are:

What is the best way to link to non-RDF resources (URIs) in Linked Data / RDF?
Which is the best vocabulary term to use for a document/resource that provides background information on the subject?

Solution

The general property for providing additional information is rdfs:seeAlso. As the spec says, you can create a sub-property of seeAlso to convey more specific semantics. As for encoding the metadata, personally I'd stick to Dublin Core and I would add a bNode so that the various properties of the external source can be recorded in the triple store.

So, if some_resource is the thing that you have more information about:

example:some_resource
  rdfs:seeAlso [
    dcTerms:source "http://your.si.te/docs/foo.html"^^xsd:anyURI ;
    dcTerms:format "text/html" ;
    dcTerms:title "Foo user manual"@en ;
    dcTerms:language "en"
  ].