On the day of, you find it on:

Television, Radio, Social Media, the Web

During the week of, you see it appear in:

Newspapers

The week after, you see it show up in:

Popular Magazines

Months after, you see articles about it appear in:

Academic/Scholarly Journals

It's usually not until a year or more later, that you see the event / topic start to appear in:

Books, Government Publications, Reference Materials

In other words...it takes time to discuss, study, understand, and integrate new events / new information, so the longer it's been since the event was first reported on, the more analyzed and nuanced the information about it will be.

This is the main reason that sources like academic articles, scholarly books, and reference works are considered the most  'authoritative', since people have simply had more time to work with and understand what used to once just be some new information, whose true impact / importance may not have yet been apparent.