The Red Book of Mathematical Problems (Dover Books on Mathematics) - GOOD

Methods of Applied Mathematics (Dover Books on Mathematics) - Paperback - GOOD

Challenging Problems in Geometry (Dover Books on Mathematics) - VERY GOOD

Ingenious Mathematical Problems & Methods by Graham, Louis A.

Boundary and Eigenvalue Problems in Mathematical Physics (Dover Books on - GOOD

The Red Book of Mathematical Problems (Dover Books on Mathematics)

Challenging Problems in Algebra (Dover Books on Mathematics) - VERY GOOD

Space Mathematics: Math Problems Based on Space Science (Dover Books on A - GOOD