1. Department of Gastroenterology and Hepatology; Erasmus MC University Medical Center; Rotterdam Netherlands
2. Department of Gastroenterology and Hepatology; Albert Schweitzer Hospital; Dordrecht Netherlands
3. Department of Epidemiology and Biostatistics; Memorial Sloan-Kettering Cancer Center; New York USA
4. Department of Public Health; Erasmus MC University Medical Center; Rotterdam Netherlands
5. Medical Library ; Erasmus MC University Medical Center; Rotterdam Netherlands
6. NIHR Birmingham Biomedical Research Centre; University Hospitals Birmingham NHS Foundation Trust and University of Birmingham; Birmingham UK