Unresolvable Identifier

arXiv:2605.06321 · detector doi_compliance · cross_source · 2026-05-19 12:48:38.389578+00:00

critical doi_compliance unresolvable_identifier

Identifier '10.3390/universe90502002' is syntactically valid but the DOI registry (doi.org) returned 404, and Crossref / OpenAlex / internal corpus also have no record. The cited work could not be located through any authoritative source.

Paper page Integrity report arXiv Try DOI

Evidence text

Grespan, M., & Biesiada, M. 2023, Universe, 9, 200, doi:10.3390/universe90502002

Evidence payload

{
  "arxiv_id": null,
  "checked_sources": [
    "crossref_by_doi",
    "openalex_by_doi",
    "doi_org_head"
  ],
  "doi": "10.3390/universe90502002",
  "raw_excerpt": "Grespan, M., & Biesiada, M. 2023, Universe, 9, 200, doi:10.3390/universe90502002",
  "ref_index": 93,
  "verdict_class": "cross_source"
}