Information can be found in a variety of sources. The main two sources that you would be using are books (and ebooks) and peer-reviewed journal articles.
Books and ebooks
Books, specifically academic books give a broader overview on your topic. Books combine, condense, discuss and analyse information from a range of sources. Books are a good starting point for any research tasks.
Peer-Reviewed Journals and Articles
Peer-reviewed journals articles are articles written by scholars in their field and are reviewed by other scholars before they are published.
Peer-reviewed articles focus on current research and are very specific. They are original, important and of a high standard.
In Primo, peer-reviewed articles have an icon saying it is PEER REVIEWED.
You can also check if the journal is peer-reviewed using Ulrichsweb global serials directory.