Hey Joyce,
That specific department asked for "one to two" sides of an A4 sheet. Each dept/supervisor asks for something different so, like Ann said, the safest thing to do is ask them directly what they are looking for.
In the statement of purpose I'm working on at the mo I describe how I got interested in my subject, what I have done so far, what I want to achieve with the PhD research and how I can use that knowledge in the future. It's a personal statement so nope, no references/bibliography here - there's hardly any space for that anyway
However, I also prepared PhD proposal a few weeks ago (for a different application) and that was much closer to a course paper format-wise and it did include references.
My personal rule of thumb is that statements of intent/purpose resemble the idea (and length) of a CV: They describe what you have done so far (plus what you intend to do in the future).