Choose your citation style with the following steps:
1. Click 'View' and then 'Citation Style'. Choose the style from the list.
2. If the style you need is not in the short list click 'More Styles...' Search for the citation style you'd like, select it and click 'Done'.
3. If you style is still not found click the tab 'Get More Styles' and search for a style to download. Select the style and click 'Install'. Then go back to the 'Installed' tab, click the style you want, and click 'Done'.