1. COPE website: History of COPE. http://publicationethics.org/about/history.
2. COPE website: Cases. http://publicationethics.org/cases.
3. Scientific Red Cards. http://www.scientificredcards.org/redcards.
4. Déjà vu: a database of highly similar citations in the scientific literature;Errami;Nucleic Acids Res,2009
5. Déjà vu. http://spore.vbi.vt.edu/dejavu/.