Citations to invalid DOI-identified entities obtained from processing DOI-to-DOI citations to add in COCI

This dataset contains a two-column CSV file, where the first column ("Valid_citing_DOI") contains the DOI of a citing entity retrieved in Crossref, while the second column ("Invalid_cited_DOI") contains the invalid DOI of a cited entity identified by looking at the field "reference" in the JSON document returned by querying the Crossref API with the citing DOI. These citations to invalid DOIs have been retrieved while processing Crossref data for adding open citations in COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. The citations listed in the present dataset have not been added in COCI since they point to a non-resolvable cited document.