Problems in Differential Equations (Dover Books on Mathematics)

Challenging Problems in Geometry (Dover Books on Mathematics)

Challenging Problems in Algebra (Dover Books on Mathematics)

Challenging Problems in Geometry (Dover Books on Mathematics)

Ingenious Mathematical Problems and Methods (Dover Books on Mathematics) - GOOD

Applied Matrix Algebra in the Statistical Sciences (Dover Books on Mathematics),

Dover Books on Mathematics Ser.: Worked Problems in Applied Mathematics

Worked Problems in Applied Mathematics by Lebedev, N. N.