An increasing number of primary sources are available for free on the web. To discover them:
1. Go to a search engine like Google
2. Combine your topic with terms designating primary sources such as primary sources, memoirs, diaries, accounts, narratives, documents, autobiographies, online archives, correspondence, speeches. Here are some examples:
Charles Darwin correspondence
Social Darwinism documents
The TVNA collection holds individual network evening news broadcasts from the major U.S. national broadcast networks - ABC, CBS, NBC, and CNN - and hours of special news-related programming, including ABC's Nightline since 1989.