Secondary Articles will summarize science research on a particular topic. They are often known as Literature Reviews because they will look at many primary articles and give an overview of the primary literature on a topic. They do NOT contain an experiment, study, or research.* If you are unsure, read the abstract (summary) of the article. Often the abstract will contain the word review or summary as a clue.
*Please remember, some secondary articles are setup like primary articles and may contain introduction, materials & methods, results, and discussion sections, but there will not be any original research, an experiment, or study done. Always read the abstract to make sure an article is just reviewing others' research.
This list of journals is a good source for secondary articles.