That question is rather vague. What are you studying that requires primary sources? Is there a certain part of the war you need primary source on? The primary sources are on the web. Certain large research universities have them available for free and others not so much. I believe Yale has some stuff you can peruse for free online. The New York Public Lib has many sources available in their databases, but you need to sign up for membership (free if you are a New Yorker) The question is hard to answer because of how vague it is.