Show HN: An interactive map of the 1M most-assigned books in college syllabi

This is absolutely fantastic. I rather enjoy learning about new subjects by going through the textbooks prescribed for University courses, so to have all of this at my fingertips... I am just giddy with excitement that this exists.

It would be nice to see which year level a textbook belongs to (Unless I'm not seeing this feature) For example, if I want to learn about Psychology but know nothing about it, I'd rather be reading books from a Year 1 University course rather than reading a book that already assumes prior knowledge on the subject.

But the hunting is part of the fun for me, too. This is an autodidacts dream.

Could this be scaled down from, say, the top 1M down to the top 10k nodes?