This depends on which Style Manual you or the institution recommends. Here's a grab from an article I'm currently writing for a curriculum. I'm using Word 2003 with footnotes and the style manual is a footnote version with a Harvard style flavour. Since I'm using MS Word, the footnotes appear at the base of the page but when I copy and paste to html here, they turn out to be ,  and  at the base of the sample I've given:
What is the size of the universe? One explanation is that
That link should give plenty of examples of citations.
Please understand that this is at a high level of research and presentation but I had to be precise (as much as possible) with the style manual prescribed. I wrote it using the MS Word 2003 word processor and the Uni has chosen to make it available online as a pdf document.
It was a requirement that if citations were longer than 3-4 lines they needed to be indented and there were no introductory and concluding inverted commas. Shorter citations could use 'single inverted commas' or they could use "double inverted commas", depending on the institution. Here's a list of Citing and Referencing guides prepared by Monash University, Melbourne, Australia.
If you would like further clarification, please ask your questions of me?