Not sure about the difference between primary and secondary sources? Watch this video:
Many primary sources have been digitized and made available on the web. You have to be careful, though, because often the source of the document is not provided. You need to evaluate each web site carefully to determine if it is reliable. In general, you can just add the words "primary sources" to your search to locate such documents on the web. The following sites are examples of what you can find on the web.
You can use the library online catalog, OSCAR, to find published primary sources or books including primary documents If you are interesting in the writings of a specific individual, just do an author search. If you are looking for primary sources on a specific topic, just enter your keywords and add one of the following words, depending on what you are looking for: correspondence, papers, speeches, memoirs, personal narratives, documents, sources.
For example: Soviet Union and sources