Think carefully about what kinds of information will exist for your movement.
Is your movement very local and involving a narrow group of people? Or is it regional, national, global? Is it so big that you need to narrow your focus?
When did your movement happen? Is it ongoing? Is it officially over, or unofficially over? Is it easy to identify the movement's roots, or not?
Your answers will help you think about what will be available. Is your movement too new for peer-reviewed articles or scholarly books? Are there a lot of primary sources that should be available? What about books? Will there be documentaries or other video content?
Take your movement and search in many different places for it. Try the article databases, catalog, newspapers, documentaries, and look for oral histories and other collections using Google.
These sources are all good for relatively recent national issues and movements. They provide readable summaries, present both sides of an argument, and cite a number of sources.
Newspapers can be considered primary sources, since they record what is happening at the time, and often include quotes, opinions or original images. However, there is a variety of other primary sources that can be useful, including the following. Think broadly.