You can use the site: command in Google to search within a particular website or domain.
The search below will locate anything on the Vox website on the topic of slavery.
You can add any website or domain to the end of the site: search operator. You could try:
CARS is a checklist for evaluating websites
Google Scholar can be a great resource for finding additional scholarly research articles!
Google Scholar recently added the ability to search case law. If you are getting weird looking results, make sure you have the "articles" button selected.
If you have an article that interests you, try searching for it in Google Scholar to see if it has been cited by anyone. This can be a really great way to find additional scholarly articles on your topic. Just click the "cited by" link under the article description. If you don't see the "cited by" link, it may mean your article is too recent.