In the box below, we present six recommendations for optimizing the indexing of preprints in bibliographic databases. As we will discuss later, implementing these recommendations requires close collaboration between bibliographic databases and other actors in the scholarly publishing system.
Recommendation 1: Cover all relevant preprint servers.
A bibliographic database should index preprints from all relevant preprint servers. A disciplinary database (e.g., PubMed and Europe PMC) should index preprints from all preprint servers relevant in a particular discipline. A multidisciplinary database (e.g., Dimensions, the Lens, Scopus, and Web of Science) should index preprints from all preprint servers across all disciplines.
Recommendation 2: Provide comprehensive preprint metadata.
A bibliographic database should provide metadata for preprints that is as comprehensive as metadata for journal articles. The metadata should at least include the title and abstract of a preprint, the names and affiliations of the authors, the reference list, and funding information. It should also include a version history.
Recommendation 3: Provide links between preprints and journal articles.
If an article has been published both on a preprint server and in a journal, a bibliographic database should provide a link between the preprint and the journal article. The link establishes that the preprint and the journal article are different versions of the same article. The preprint and the journal article belong to the same publication family.
Recommendation 4: Provide links between preprints and peer reviews.
If a preprint has been peer reviewed and the reviews have been made openly available, a bibliographic database should index the reviews and should provide links between the preprint and the reviews.
Recommendation 5: Provide deduplicated citation links between publication families.
A bibliographic database should provide deduplicated citation links at the level of publication families. If there are multiple citation links from publications in one publication family (e.g., from a preprint and from a journal article) to publications in another publication family, these citation links should be deduplicated.
Recommendation 6: Do not make arbitrary distinctions between publication types (preprints, journal articles, and others).
A bibliographic database should not make arbitrary distinctions between preprints, journal articles, and other publication types. A database may inform its users about relevant differences between publications of different types (e.g., whether publications have been peer reviewed or not), but otherwise it should treat all publications in the same way, regardless of their publication type.