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This disclaimer relates to PubMed, PubMed Central (PMC), and Bookshelf. These three resources are scientific literature databases offered to the public by the U.S. National Library of Medicine (NLM). NLM is not a publisher, but rather collects, indexes, and archives scientific literature published by other organizations. The presence of any article, book, or document in these databases does not imply an endorsement of, or concurrence with, the contents by NLM, the National Institutes of Health (NIH), or the U.S. Federal Government.

Please see more below about our content and how our databases relate to you.

Literature Database Content

Content in NLM literature databases may be published by academic publishers or institutions, scholarly societies, or government and non-governmental organizations. To be added to a database, a publication must apply and be selected by NLM for inclusion in MEDLINE, PMC, or Bookshelf. PubMed indexes and makes searchable the contents of these databases; MEDLINE is the primary component of PubMed. Details on the content selection processes for each database can be found at:

Once publications are selected for inclusion in a database, NLM does not review, evaluate, or judge the quality of individual articles and relies on the scientific publishing process to identify and address problems through published comments, corrections, and retractions (or, as in the case of preprints, withdrawal notices). The publisher is responsible for maintaining the currency of the scientific record and depositing all relevant updates to the appropriate NLM database. NLM literature databases also archive and index articles, author manuscripts, and book chapters that may be from publications that have not yet undergone scientific review by NLM, are traditionally out of scope for the NLM collection, or have not met NLM’s standards for inclusion in a given database if a paper is deposited under


PMC and PubMed also include preprints reporting NIH-supported research in support of the NIH Preprint Pilot. As preprints are interim research products that have not been peer reviewed, readers should be aware that any aspect of the research, including the results and conclusions, may change as a result of peer review.


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Last modified: Mon Aug. 28 2023