When deciding what types of sources would best meet your needs, it is helpful to understand the information timeline. When an event happens, information on that event gets filtered down through different sources. As it gets farther down the information timeline, the more that event is analyzed.
The initial information that is disseminated includes quick facts and interviews about the event that is published in the news and online. As time progresses, the information is studied in more depth and is then published in journals or books.
View this video to learn more about the Information Timeline and Types of Sources:
So if you have a new or recent topic, you are not likely going to find much in journals or books. Also, information that comes out initially may or may not be properly verified and might be biased based on who is reporting it. As information progresses down the timeline, it is looked at in more depth and is then published in scholarly journal articles and books. For this reason, most instructors prefer you to use scholarly journal articles and books as your sources.