The correct answer to this open question is the following.
Although the previous link was not attached, we can say the following.
The central ideas or information of a primary or secondary source are the following,
A primary resource comes from the people who witnessed the event, the incident, or the specific moment. These people could have written their own descriptions, testimonies, books, or maybe journalists that directly reported what happened. It also could be an interview with people who were part of the historical event. For instance, if it is a soldier that participated in the Vietnam War, a journalist can interview him and use it as a primary source.
On the other hand, secondary sources can be obtained from other sources that were not direct. This could be an author that based its story in other investigations, or it could be encyclopedias.
