1. VU University Medical Centre; Department of Obstetrics and Gynaecology; Research Institutes ‘ICaR-VU’ and ‘Reproduction and Development’; Amsterdam the Netherlands
2. Department of Obstetrics and Gynaecology; Deventer Hospital; Deventer the Netherlands
3. Department of Epidemiology and Biostatistics; VU University; Amsterdam the Netherlands
4. Medical Library; VU University; Amsterdam the Netherlands