Below are some websites that will either list or give access to available Korean language primary documents for perusal.
Below are the links to some of foreign affairs documents collections available online.
Below is the list of links to some Korea related FRUS (Foreign Relations of the United States) volumes:
If you are searching for works by famous political leaders, you can perform a catalog search by the author. You can also use “speeches” or “works” as an additional keyword.
Another way to search for sources in the Catalog is to search by a combination of keywords like, for example, [country] AND [additional keyword] AND [sources] OR [documents]. For example, to search for documents on Soviet-Korean relations you may try to search for Korea AND Soviet Union AND documents.