1. Department of General Oral Health Care, Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Amsterdam The Netherlands
2. Department of Orofacial Pain and Dysfunction, Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Amsterdam The Netherlands
3. Medical Library Vrije Universiteit Amsterdam Amsterdam the Netherlands
4. Department of Conservative & MI Dentistry Unit of Distance Learning, King's College London Faculty of Dentistry, Oral & Craniofacial Sciences London UK
5. Radboud University Medical Center Radboud Institute for Health Sciences, Department of Dentistry Nijmegen The Netherlands