In all academic works, including dissertations and theses, it is essential to provide evidential support for the points you are making. This typically means referring to the work of others using citations that state the author(s) of such works and the date on which it was published, e.g. Jones (2020). For some referencing systems, such as Chicago and OSCOLA, it is sufficient to use numbers to denote references, write the references in the footnotes, and then provide a full list of references at the end of the work. For other systems, most notably Harvard and APA, the convention is to cite the author(s) and date in the text, and then provide a full list of references at the end in alphabetical order.

However, there can often be more than one author of a work, and in some instances (most notably in medical or certain scientific fields), the number of authors can run into double figures. Citing every author of a piece of work can become problematic as it makes a thesis or dissertation extremely difficult to read and, if there are word counts to be adhered to, can mean that important content is sacrificed to make way for an extensive list of names. This is considered neither necessary nor desirable, and the way academia gets around this problem is to use the phrase ‘et al’ (which literally means ‘and others’) in place of a long list of authors. For work complying with APA guidelines, the rule is to use ‘et al’ when there are three or more authors of a text. If there are one or two authors, then their names can be written in full, e.g. Jones (1987) or Williamson and Potter (1976). For an article with three authors or more, the rule is to cite the first author followed by ‘et al’ and then the date, e.g. Clarke et al. (1976). The rule is the same for Harvard, except that ‘et al’ is only used when there are four or more authors. Hence, you can refer to Wayne, Hart and Jones (1996), whereas in APA this would be Wayne et al. (1996).

Two stylistic rules need to be noted in relation to the use of ‘et al’. Firstly, when the work is the subject of the sentence, the reference is as follows: “Blake et al. (1987) found that the rate of prejudice was high”. However, when the sentence focuses instead on the main finding, the authors and date are included in brackets, as the following example demonstrates: “The rate of prejudice has been found to be high (Blake et al., 1987)”.

Note that there is no comma before ‘et al’, no comma between the two words (a common mistake), and there is always a full stop at the end. When cited in brackets, the full stop is followed by a comma and then the date (as shown in the above example).