The University of Waikato Library does not provide guides to Harvard Style. If you have been advised to use this style, we recommend you consult the guides of academic libraries which do. For example:
Harvard Style is an author-date system which uses parentheses e.g. (Holton 1987, p. 245) or (Holton 1987: 245). Note that formatting and punctuation may vary by institution. There is no one definitive source for the Harvard style. It originated in 1881 when a professor of zoology at Harvard University started using parenthetical references as described in the article The 'Harvard System': A Mystery Dispelled.
Harvard University explains that the Harvard Style is not actually used at the institution from which the name derives (see About the "Harvard Style")