Excellent choice of books. I do think you may wish to link to some smaller booksellers rather than feed the Amazon monster.
Avoid “abebooks" which is Amazon under a different name.
These are just some examples. You can find more with a Google search.
Yes, I know Google is a monopoly; however, Google does not directly compete with their vendor partners, or undersell their vendor partners, or run sweat shop operations where the workers get repetitive stress injuries and Amazon refuses to cover medical expenses. In fact, to resolve the issue, Amazon just terminates the worker for poor performance after the injury.
If you can avoid promoting Amazon, please do.