Not a well written web site. It is much easier to see the links and follow your nose on the web, if the authors have put them there. I don't think we are there yet but I can hope for a day when that will be true.
Though, google (and the like) itself tends to allow you to hop around and find new things. All (ha! all indeed) is that one has the kinds of unbounded curiosity you brought to bear. My daughter has some of that, my son less so.