If there is an article that you really need or want, you can request it (most often for free) through interlibrary loan. Expect it to to take up to 10 days to receive item electronically via email.
When you need to find several articles, you can use the snowball technique to find older sources (look in the article bibliography) or find newer sources (use Google Scholar's 'Cited by' feature).
You can search within the abstract to limit your search. You can also use the word 'study' and limit it to the abstract to get original studies in your results. There are other ways to identify original research, but this is one shortcut.
