[justinberding]

That's a great question. I can't say for sure that Goodreads was part of Amazon's affiliate program prior to them being acquired in 2013, but I don't see why they wouldn't have been.

Booqsi is specifically not part of Amazon's affiliate program and instead of focused on the local bookstores via bookshop.org, so I'm not an Amazon affiliate expert, but I would imagine that Amazon wouldn't have any issue with a site like this linking users to purchase books from them.