I noticed that when I export a collection to Zotero RDF, journal articles get a reference to the journal's ISSN-as-URN:

<dcterms:isPartOf rdf:resource="urn:issn:1936-1955" />

This says an article is part of a journal, which seems semantically correct to me, but the journal identified by the ISSN is described as an issue:

<bib:Journal rdf:about="urn:issn:1936-1955">
  <dc:title>J. Data and Information Quality</dc:title>
  <prism:volume>2</prism:volume>
  <prism:number>2</prism:number>
  <dc:identifier>DOI 10.1145/1891879.1891883</dc:identifier>
  <dc:identifier>ISSN 1936-1955</dc:identifier>
</bib:Journal>

This appears semantically incorrect. An article is part of an issue, that is part of a journal. (Well, it may be part of multiple issues of multiple journals, depending on how you define article, but that's beside the point I'm trying to make.)

The above description of a journal mixes assertions about the journal and the issue by assigning a volume number, issue number and DOI to the whole journal.

The ontology at http://vocab.org/biblio/schema doesn't have a class for "issue" and I haven't studied other vocabularies very well to see how they might handle this.

May I propose to alter the first dcterms:isPartOf reference to a URI that identifies the issue? This new URI should probably be outside the URN space.
A description of the issue can then have a reference dcterms:isPartOf rdf:resource="urn:issn:xxxx-xxxx" and a description of the journal like this:

<bib:Journal rdf:about="urn:issn:1936-1955">
  <dc:title>J. Data and Information Quality</dc:title>
  <dc:identifier>ISSN 1936-1955</dc:identifier>
</bib:Journal>

Regards,

Ben