50 usd for a hard cover text book isn't exactly expensive

https://www.amazon.com/Art-Computer-Programming-Vol-Fundamen...

I would love to go with The Art of Computer Programming.. but I am already confused reading that page. Is this:

http://www.amazon.co.uk/Art-Computer-Programming-Fundamental...

part 1 or is this:

http://www.amazon.co.uk/Computer-Programming-Fascicle-MMIX-M...

You should probably add Knuth's Volume 1 ( Fundamental Algorithms) to your list: http://www.amazon.com/Art-Computer-Programming-Fundamental-A...

The first few sections cover some mathematical background.