Keep in mind that your topic may have been described differently at the time of the events. For instance, during World War II, it was not called that.
Use encyclopedia articles to learn more about how your topic was talked about at the time before you get frustrated in searching. Try also to use alternate keywords like the names of people or treaties, etc.
Also, some of your topics were state secrets at the time - no one knew about them until years later. Your primary sources will not be news sources, but declassified files.
TIP: Stay organized as you search. Record good keywords or search strings. Email yourself articles that seem promising. It's easy to forget where and how you found something when you're dividing your time between so many classes and assignments.
