Another way to find important primary sources on your topic is to find a literature review and then look at the cited references.
1. Click on the Refine Search tab or link which displays above the record(s).
2. Scroll down the page until you see the Methodology dropdown menu.
4. Select literature review.
5. Click Search. Now your search will only retrieve literature reviews on your topic.
6. Click on the title The Development and maintenance of post-traumatic stress disorder... You can tell from the abstract that this is a review article.
7. Click on the Cited References link to see what sources this article used.