Looking for more recent articles? Try citation tracking.
There are two main ways to do this:
One way is to follow references backward. You can do this by looking at the references at the bottom of the articles you have already cited. There is likely to be at least a couple of promising articles. Look those up. The second way is to follow references forward. Some databases allow you to look for a particular article and see what papers have cited that article. Look at the list of those articles and you are likely to find a few articles that relevant to your research. Look those up.
Keep in mind:
When following references backward you will be finding articles that are OLDER than the article you used.
When following references forward you will be finding articles that are MORE RECENT than the article you used.
Here is an example of following citations forward (finding more recent articles) from GoogleScholar. Other ways of searching by date are also noted. In some databases there are similar features: