- Author: Erik de Haan (auth.)
- Language: English
- Year: 2005
- Author: Erik de Haan
- Language: English
- Year: 2006
- Author: Erik de Haan
- Language: English
- Year: 2005
- Author: Erik de Haan
- Language: English
- Year: 2006
- Author: Erik de Haan Yvonne Burger
- Language: English
- Year: 2005
- Author: Erik de Haan
- Language: English
- Year: 2008