Journal articles are considered a very reliable resource for information on a topic and instructors will expect you to rely more on journal articles as you move along in your college career.
Here are some reasons why.
In journals:
In magazines and newspapers:
These are some common rules of most databases:
Studying your search results is a great way of finding more relevant keywords, removing irrelevant terms, and looking for additional resources in article bibliographies. You can also follow author names to see if they have written more on this subject and what authors they have cited.