Save citations as reference list in standard CSL-JSON or BibTeX format

[diegodlh]

Currently, citations are saved in a Citations note attachment. Each citation has metadata about the cited item (in Zotero API JSON format), a list of OCIs, and the ID of the Zotero item it is linked to.
This format is non-standard.

Consider saving citations in a References note attachment. This would contain a list of BibTeX or CSL-JSON references. That is, the cited items' metadata.

A separate attachment (or extra field) would have the list of OCIs.

This way:

• references would be more saved in a more standard way, and could be imported and exported without Cita;
• the Citations Pane would list references in the References attachments (if more than one, the union could be listed Better handle items with multiple citations notes #81);
• using the OCI list, it would known if the citations listed are available in external suppliers or not;
• if there is an OCI in the list not matching any reference, it would be an OCI without cited item metadata. It may be listed at the end of the citation list without metadata, and it would be offered to get metadata of cited item. This would fit with the sync with Wikidata process: First step would be get the OCIs from Wikidata and update the OCI list. If there are items with the target QID in the references attachment, mark the as available in Wikidata (one problem would be that it won't know if an item marked as available in Wikidata is no longer there, and maybe user wants to remove it locally). Then, automatically download cited item metadata for the other OCIs retrieved.

CSL-JSON may be preferred over BibTeX, because it has an ID field. This field is filled with the Zotero Key when using CLS-JSON export. Hence, it would be useful to store the linked-to-Zotero-item information. In addition, it would also simplify fixing #39. If cited item not linked to Zotero item, maybe use "ref_1", "ref_2" etc as used by CrossRef XML.

There are BibTeX to CSL-JSON convertor tools out there. That would simplify fixing #4 #61

To make this easier, it is critical that a de-duplication option be available, to merge references (in the references attachment) #37

Alternative standard formats for references may be:

• CrossRef XML. This is what is used to deposit references in CrossRef (https://www.crossref.org/documentation/content-registration/descriptive-metadata/references/#00177). Scholarcy extraction can output this. Supports "unstructured citation". Maybe item types are limited.
• BibTeX: it's widely used, but the downside is that it doesn't support Zotero keys. There are BibTeX -> CLS-JSON converters