You need to provide a complete bibliography which lists everything that you have read for your essays or dissertation. References are important academic tools to use within the essay format. This includes books, journals, web pages that you have referred to. Referencing helps your readers find those sources if they want to research material in the same field. It also helps you make clear that you are not trying to portray the ideas of other academics as if these were your own ideas and is therefore vital in avoiding plagiarism.