Research articles and non-research articles (e.g. Opinion, Review, and Commentary articles) must cite appropriate and relevant literature in support of the claims made. Excessive self-citation, coordinated efforts among several authors to collectively self-cite, gratuitous and unnecessary citation of articles published in the journal to which the paper has been submitted, and any other form of citation manipulation are inappropriate. 

Citation manipulation will result in the article being rejected, and may be reported to authors’ institutions.  Similarly, any attempts by peer-reviewers or editors to encourage such practices should be reported by authors to the publisher. 

Authors should consider the following guidelines when preparing their manuscript:

• Any statement in the manuscript that relies on external sources of information (i.e. not the authors' own new ideas or findings or general knowledge) should use a citation.
• Authors should avoid citing derivations of original work. For example, they should cite the original work rather than a review article that cites an original work.
• Authors should ensure that their citations are accurate (i.e. they should ensure the citation supports the statement made in their manuscript and should not misrepresent another work by citing it if it does not support the point the authors wish to make).
• Authors should not cite sources that they have not read.
• Authors should not preferentially cite their own or their friends’, peers’, or institution’s publications.
• Authors should avoid citing work solely from one country.
• Authors should not use an excessive number of citations to support one point.
• Ideally, authors should cite sources that have undergone peer review where possible.
• Authors should not cite advertisements or advertorial material.