Start searching for your anchor article in a multidisciplinary database using search terms. Once you've found a few potential articles you can look at the journal title and author identifiers to help determine what discipline it is from.
The video below show how to search using the database Academic Search Complete from Ebsco. The search strategies in the Ebsco interface are almost the same in the ProQuest Research Collections interface! This includes the following:
Use this drop-down list to select a discipline that may relate to your research question. This will connect you to the best databases for that discipline.
This short video explains that different types of articles "out there", and how and when you use them!