As you search, concentrate on finding a variety of genres on your topic. Diverse genres will contribute different types of information and perspectives to help you better understand the topic you are researching.
The sources you choose should represent different rhetorical stances in terms of purpose, audience, type of appeal (ethos, logos, pathos), authority, etc.
Below are different options to find diverse genres.
Academic Search Premier can be used to find varied article genres: from newspapers, magazines and scholarly journals. Here is a link to a quick tutorial on how to use Academic Search Premier.
Newsbank provides articles from over 900 U.S. newspapers