This page will assist you in locating primary sources for your topic.
A primary source in history is an artifact or document that is contemporary to the time period you are studying.
Search Library Search to find books by a particular person using the "Advanced Search" author field, e.g. "Havel, Václav." You might also want to limit the language to "English".
Try a broad keyword search, adding keywords such as "sources", "correspondence", "documents", etc., e.g., Cold War AND Sources.
Now is a great time to be researching history. Every day, more and more content that was previously accessible only in special collections and archives is now being scanned, digitized, and posted on the web. The links below represent only a handful of such digitization projects on the topic of European history.
Books published before 1926 are in the Public Domain, so the full-text of many historical books may be found via Google Book Search.