[sfsylvester]

It's a great read. I have also found a great reading list of from the University of Cambridge[0] that has a whole different range of books and websites for those who have a cursory interest in Mathematics.

[0] https://www.maths.cam.ac.uk/sites/www.maths.cam.ac.uk/files/...

[math123]

Slightly updated version of the list at https://www.maths.cam.ac.uk/documents/reading-list.pdf/