Most of the articles will have an abstract. This is a short paragraph at the head of the article that lists the main facts and arguments in each article. By reading these you will quickly get the gist of what each article is about and where it fits into the pattern you are building up in your literature survey.
How many books and articles should you have? It’s wise to check this with your lecturer or tutor. In general, though, your aim is not to cover every single book or article, but every major opinion or theme on the topic. Many of the books or articles will add very little that is new.
Therefore a short list of really scholarly, relevant, comprehensive articles is often more effective than a list of hundreds of superficial or tangential articles.
What you are ideally looking for are the “seminal” articles (seed articles) on which most of the other authors are basing their work.
Next topic: Step 4: Group articles by themes