There are a couple of places where you can access citations for articles found within PubMed.

1. Search Results page - Click the Cite link beside the result

2. Article Details page - Click the Cite button under 'Actions'

Clicking the Cite link or button will open the Citation Text pop-up. Here we can see a preview of the citation. There are actions across the bottom of the box.
- Click COPY to copy and paste the citation into a document
- Click DOWNLOAD .nbib to import the citation into a reference management tool such as RefWorks (More about RefWorks)
- Click the FORMAT dropdown to change the citation style from the default to APA, MLA, etc.