Adding to that, with all of the various third parties, and co-mingling of inventory on Amazon, I don't feel like the odds are good that I'm not getting a counterfeit item. No way would I trust a food/vitamin or anything that touches food from Amazon. So I try to only buy books from Amazon, but even that must be getting pretty bad, since I just came across this disclaimer as the very first sentence of a book's description:

"All legitimate copies of VDGF produced by Princeton University Press are crisply printed on high-quality paper. If you obtain a shoddily printed copy, it's a fake: please return it and purchase a genuine PUP copy."

https://www.amazon.com/Visual-Differential-Geometry-Forms-Ma...

If you want an "intuitive" approach, you might check out this new book: https://www.amazon.com/Visual-Differential-Geometry-Forms-Ma....

Disclaimer: I haven't read it (but I have heard good things).