- Author: Hella Olbertz (editor), Pieter Muysken (editor)
- Language: Spanish, Castilian
- Year: 2005
- Author: Evelien Keizer, Hella Olbertz
- Language: English
- Year: 2018
- Author: Hella Olbertz
- Language: English
- Year: 1998
- Author: Hella Olbertz
- Language: English
- Year: 1998
- Author: Hella Olbertz Kees Hengeveld Jesús Sánchez García
- Language: English
- Year: 1998
- Author: J. Lachlan Mackenzie Hella Olbertz
- Language: English
- Year: 2013