Tricky exercises for Calculus II, where can I find them?

Question

I'm getting myself ready for university exam of calculus II, but I'm struggling to find exercises that are difficult enough to be really prepared for an exam. The topics I'm interested to are:

• Tangent plane and normal vector to a surface
• Maxima and minima research for multivariable functions
• Partial derivatives and gradient vector
• Double and triple integrals

Thanks for any reference (also online PDFs are OK)

Answer 1

References for optimization (finding maxima and minima)

Boyd, Stephen, and Lieven Vandenberghe. Convex optimization. Cambridge university press, 2004.

Wright, Stephen, and Jorge Nocedal. "Numerical optimization." Springer Science 35.67-68 (1999): 7.

and for some calculus

Stewart, James. Calculus. Cengage Learning, 2011.