Collect reference information. As you prepare to write your essay, take note of the bibliographic information for any book or journal article you read. You'll need to know the author, title, date, publisher and place of publication. For journals or magazines, you'll also need to know the volume and issue number. For online sources, note down the address and the date on which you accessed the information. Record the page numbers of any statements you wish to cite.
Find out which referencing format your school, university or department wants you to use. There are a number of standard referencing styles, such as those published by the American Psychological Association (APA) or the Modern Language Association (MLA). This will tell you how to format your references.
Insert citations into your text. Every time you draw on the work of another source, refer back to it. There are two main ways of doing this. You might insert an in-text citation, which follows the cited text immediately with the name of the author and date of the work. Alternatively, you may use a footnote or endnote. In this case, a small superscript number follows the text, leading the reader to the reference information, which is either at the bottom of the page or the end of the essay. Which type of reference you use depends on the referencing style.
Write a bibliography for your essay. This is a list of all the works cited in your essay, listed alphabetically by the author's last name. The exact format of the entries in your bibliography is determined by the referencing style.