Authors should be presented in the order that they appear in the published article. If they are cited within closed brackets, use the ampersand (&) between them. If they are not enclosed in brackets, then use the spelled out “and.”
Examples:
A well-known study argued that social class is rapidly becoming obsolete (Calvert & Liu, 1987).
Calvert and Liu (1987) argued that social class is rapidly becoming obsolete.