On the library database LibGuide the top link is to Academic Search Ultimate. When you click on this link, it will ask you to log in. Use your student ID # and 4X4.
On the search page, enter Puerto Rico in the top search bar and change the "Select a Field" to the right of the search bar to "Subject Terms" then enter United States in the second search bar and also change that to "Subject Terms". You will get results that include both Puerto Rico and United States as main subjects of the article.
To narrow the search down, on the left side navigation bar under "Limit To" select the "Full Text" box. That will make sure all the results have full-text articles that you can access.
You can also narrow down the date if you would like a specific time period. Be aware that the time period refers to when the article was published, not the time period the article is about.
The "Publication Type" lets you choose if you would like an academic journal, a peer-reviewed article, or a magazine if you would like to narrow the results down even more.