Back when I was an undergraduate, taking a course like calculus, I had so many available resources at my disposal: suppose I wanted to learn more deeply about the mean value theorem, which was just introduced in a lecture. I could find very detailed descriptions on Wikipedia and some calculus books like Rudin's, Spivak's etc...
Now, going beyond the scope of undergrad, suppose I want to learn about the "connection problem" in the field of differential equations. Googling the term doesn't result in a nice Wikipedia article anymore (in fact it gives results discussing internet problems). Using Google Scholar results only in particular cases of connection problems.
Basically my questions/requests are:
How can one learn about a new (for the reader) mathematical term in the postgraduate setting, when it doesn't appear on Google, or in some classical book.
My understanding is that mathematical articles help with the reduced access to books and Wikipedia/MathWorld pages available for postgraduate topics. How does one orient themselves in the setting of mathematical papers? I know that the paper itself has references to earlier works, and that on Google Scholar you can see which papers have cited the current paper later on. This allows one to think of mathematical papers as a graph, where citation between papers corresponds to an edge between the two. Hence, studying a new topic/term is like a walk on this graph. Is this the typical way to get around?
If there are any other popular methods that help with studying postgraduate mathematics in particular, please let me know.