Different types of sources are suited for different purposes. Knowing what kinds you need can help you search more effectively.
Always refer back to your assignment for which types of sources will fulfill your requirements.
Journal articles in scholarly journals are peer-reviewed because other experts in the subject area review these articles before they are published. The publication process can take a year or more, especially if the author(s) needs to make many edits. Scholarly publications are written by scholars in a particular field.
Popular sources are written for a general audience. The most common examples are magazine and newspaper articles. Generally, popular magazines focus on entertainment, current events and special interests topics (health and wellness, hobbies, etc.). Articles for popular sources are typically written by journalists or freelance writers.