One of my favourite sources for information and guidelines regarding referencing and citation styles is the Purdue Online Writing Lab (OWL). I have heard several professors (in the humanities, at least) recommend it to graduate students. But there are also several other resources student researchers and academics can draw on to hone in their research writing skills. This page from Plagiarism.org features a plethora of excellent materials and citation sources that are all available online or in the form of PDF documents , free to download and use.
Via Elizabeth E Charles