Propaganda - Vietnam War

Hello

So far, I have decided what to write about and started the search for sources.
My subject is propaganda during the cold war but I have limited it to one question: How USA used propaganda to justify war in Vietnam. I chose it because I wanted to really explore propaganda, or at least parts of it, during the Cold War. We have studied the Cold War for a while but I haven't learned anything about the propaganda. As this was a war of propaganda more than real fighting I thought it would be great to get this knowledge too.
After I had decided my subject I had to start finding sourcesto work with. So I started to look for pages on Internet, but I didn't find that much good information. Except for one page (http://history1900s.about.com/library/photos/blyviet29.htm) with a quite horrible propaganda poster which show what strong feelings USA used to get people into the war.
I have also been to Hedbergskas library, but I haven't had time to read all through yet, so I don't know if it is any good sources for me.

Linda Ekmarker