Answered By: Rebecca Mackle Last Updated: May 18, 2018 Views: 163
You should cite any article written by two or three authors by including all the surnames every time you cite them. This is explained further in the guide to Harvard referencing under the section 'Citing references in text', 'Two or three authors for a work': Harvard Guide
You should only use et al when citing an article with four or more authors as this will save on your word limit.
For more information on Harvard Referencing, please use the Anglia Ruskin Harvard Guide.