You can earn a 5%
commission by selling Numerical Techniques for Boundary Element Methods: Proceedings of the Seventh Gamm Seminar, Kiel, January 25-27, 1991 (Notes on Numerical Fluid Mechanics)
on your website. It's easy to get started - we will give you example code.
After you're set-up, your website can earn you money while you work, play or even sleep!
You should start right now!