1. Publication bias: a problem in interpreting medical data;Begg;J R Stat Soc A,1988
2. Publication bias;Begg,1994
3. The Cochrane Reviewers' Handbook 4.2.0. The Cochrane Library,2003
4. Undertaking systematic reviews of research on effectiveness: CRD's guidance for those carrying out or commissioning reviews. Report 4,2001
5. Identifying relevant studies for systematic reviews;Dickersin;BMJ,1994