When you have a source with a bibliography, you can see if a particular article from the bibliography is available by looking the journal's name up at the link below. Then you can use the volume and date information to navigate to the article. If we don't have access to that journal, we usually can get it from another library.
As you find books and articles, pay attention to what the author of a useful source says about other scholars in the field. Most scholarly articles and books have a section where they discuss the scholars that impacted their own present work. Look for phrases like "So and so is a key leader in the field" or "So and so's methodology impact our work in significant ways" or "We disagree with so and so in these ways."
Note the scholars that your original source describes as significant. Then go find the books and articles those scholars wrote. This is how you trace the conversation happening around your topic.
By tracing cited works, you will find connections that you would otherwise miss. You will discover the patterns of the conversation around your topic. This is the way most scholars search for sources, so if you also search this way, you'll be searching in a very sophisticated and informed manner.
How to do a bibliographic trace: Search for cited books by title or author in library catalogs; for journal articles, check the Do We Have This Journal by journal name to see if we have the full text of an article. Several databases also include features telling you how often a work has been cited (like the ones below). Use Tracking Down Materials for more pointers on how to find hard copies. Please also contact me or any other librarian if you need help at any point of this process.
You can (and should) also go forward in time to see who has cited your original source.
