Two of Vernor Vinge's books in particular (science fiction): A Fire Upon The Deep, and A Deepness In The Sky.
They have a special place in my heart. Vinge didn't write much, but what he did write I think is very special indeed.
I've also taken to buying hardbacks of my favourite books from ebay.
https://www.goodreads.com/en/book/show/77711.A_Fire_Upon_the...
https://www.goodreads.com/book/show/226004.A_Deepness_in_the...