1. Online test material, for all levels: (theory in short, exercises and assignments); can be found on www.4mules.nl
2. For students Economics or Management science: Knut Sydsaeter, Essential Mathematics for Economic Analysis, 4th edition
Excellent book that is used at Erasmus University Rotterdam.
Gerald Keller Statistics for Management and Economics, 10th edition
An excellent book with many examples and exercises with solutions; it is used at Erasmus University Rotterdam.
The website 4mules.nl is ideal for students who want to quickly understand and master a number of important topics in mathematics. It contains many examples and a large number of exercises with solutions.