Elementary books by good mathematicians I'm interested in elementary books written by good mathematicians.
For example:


*

*Gelfand (Algebra, Trigonometry, Sequences)

*Lang (A first course in calculus, Geometry)


I'm sure there are many other ones. Can you help me to complete this short list?
As for the level, I'm thinking of pupils (can be advanced ones) whose age is less than 18.
But books a bit more advanced could interest me. For example Roger Godement books: Analysis I & II are full of nice little results that could be of interest at an elementary level.

Calculus by Michael Spivak.
It's very rigorous, but it starts from ground zero. 
