This is beautifully done. I'm happy about your successful implementation and half annoyed that now, I'm going to get even more books in my "to read" list. :-|

This is beautifully done. I'm happy about your successful implementation and half annoyed that now, I'm going to get even more books in my "to read" list. :-| Back when I worked on openlibrary, we had something called "subjects" (e.g. https://openlibrary.org/subjects/architecture https://openlibrary.org/subjects/architecture) and at the bottom, it would give out "Related..." books (by subject, place etc.). It was an extremely simple algorithm but gave me quite some nice things to follow. Good work!