Nowadays few scientists would dare to submit an article entirely without references. An unreferenced scientific text appears naked and incomplete, its contents unattested and unauthoritative. References are tools for the dissemination of knowledge, preservation of standards and recognition of previous contributions. 1 But what other functions are served by references, and what lurks behind them? This paper explores the development and the uses, misuses and abuses of references in scientific publications. ORIGINS Long ago, anagrams, lectures, unpublished letters and sealed notes were amongst the means by which scientists sought to communicate yet also protect their intellectual property. 2 It is through citation, however, that priority and the efforts of others are most readily acknowledged, and the reference as a method to document sources probably dates from the Italian Renaissance. 3 But references represent more than just an economical device whereby a writer refers back to the corpus of preexisting knowledge. By formally recognizing the contribution of his predecessors, the writer avoids possible charges of plagiarism or of expressing merely unsubstantiated or eccentric opinions. Whilst providing the background that makes the text respectable, the reference at the same time permits the author to claim originality. 4 References can also serve another function. In many reviews or analyses today, they are less an underpinning than the structure itself. Evidencebased medicine depends on the systematic evaluation of multiple references arranged in hierarchies of reliability.