“The opening up of citation data is welcome. It means greater transparency and accountability for research studies designed to inform academics, funders and governments in their decisions about areas of research they should focus energy and money on.
But more is needed. Not all publishers index papers on Crossref, and not all indexed papers have citation data associated with them. One study published in July found that about one-third of papers indexed in 2021 are lacking such data (N. J. van Eck and L. Waltman. Preprint at https://doi.org/10.31222/osf.io/smxe5; 2022). Some of these articles — particularly editorials, letters, corrections and book reviews — might not have any references, but this by no means applies to all of them. Uploading citation data should not be seen as optional….”