the criminology and criminal justice network
At City University, I often have to go through with undergraduate students the Harvard system of referencing, recently I have been directing to them to this site:
It is brilliant. Loads of examples and description!
in relation to referencing, I found some time ago a Firefox App that is wonderful.
It's called Zotero and help to fetch all the infos about a page and add it to your reference list in 1 click only.
it's the most efficient I have found so far!