When we talk about primary source documents for your assignment, we are looking for documents that were most likely produced during the Cold War and by people directly involved in the Cold War. You are looking for documents that are a product of their time, in a sense.
This guide will help you think through ways of finding primary source documents, as well as secondary sources that might help you interpret your documents. You might also want to take a look at the Primary Sources library guide.
You'll find my contact info on this guide; that's not a mistake. I'm a resource for you as well. Feel free to contact me with questions about your research, including any issues you're having or if you want to bounce ideas off of someone.
A quick note about finding archival material. Many archives and research centers - especially larger ones like this - have digitized and made available many important resources online. This is really amazing. Before this kind of work happened, you would have needed to travel in person to each archive to access materials.
Note that not everything in every archive is available online. So you still might find that you can't access something you want to access. In this case, send me an email or come see me (or any of my colleagues) at the reference desk. We might be able to find some other ways of accessing what you're looking for.
Presidential Libraries are treasure troves of documents and other primary sources. I've listed the homepages for each Cold War US President's library below. When you search these, look for a link to search their online documents and/or online collections, and/or digital collections. (As a reminder, not every document in each library has been posted online.)