Perhaps you've seen these mind maps that help you think about the connections between ideas.
A Table of Contents in a book can serve a similar purpose. When you click on a book title in HamCAT, often you'll be able to see the Table of Contents for that book. And, if the book is an ebook, you can click on the chapters and move to the content that interests you. Even if you don't read the entire book yourself, what the author includes (or doesn't) and how they arrange it in their book tells you something about how they define the topic of their text.