Sources with multiple authors
Where sources have two authors, include both surnames separated by 'and' in the citation. In the case of more than two authors, only the name of the first should be included, followed by 'et al.'.
In a recent study (Wilson and Brown 2005, pp.20-67), two-thirds of Bristol students were found to have eaten sausages at least twice per week during term time.
The most important advance in our understanding of British sausage consumption trends took place in the decade after the publication of the findings of the Bristol Sausage Survey (Neville et al. 1990).
Sausages account for a very large part of most students' overall protein intake (Smith and Franklin 1992, p.23).
Neville et al. (1990, p.56) have argued that the decline in sausage consumption in Britain in the late 1980s was due to the growth in popularity of the American burger chains such as McDonalds and Burger King.