Authors are required to follow referencing styles in academic writing. The Harvard style of referencing uses an author-date format for citations. Unlike other referencing styles, the Harvard style of referencing differs between institutions. However, there are two elements in Harvard style: in-text citations and a list of references. Harvard style referencing is used in a wide variety of disciplines. Although there is no definitive version of Harvard referencing available, the author-date format increases the credibility and currency of the resources used. Since no definitive style of Harvard style is available, institutions frequently publish guides for it.