Hi Krystle-Jayne

If it's in Harvard UTS style the answer is that if there are 4 or more authors, list the first author and abbreviate with et al. (Note that all the authors must still be listed in the reference list at the end of your document). In other words "According to Tan et. al.'s (2010) conference paper, ...'

This information comes from our webpage: http://www.lib.uts.edu.au/help/referencing/harvard-uts-referencing-guide/more-information

If it's in APA style it's a different answer. When a work has 3,4 or 5 authors cite all authors the first time; in subsequent citations, include only the surname of the first author followed by et al. and the year.

Janice