11.11  References

Clarke 2006 
Clarke M, Hopewell S, Juszczak E, Eisinga A, Kjeldstrøm M. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database of Systematic Reviews 2006, Issue 2. Art No: CD004002.

Deeks 2001 
Deeks JJ, Altman DG. Effect measures for meta-analysis of trials with binary outcomes. In: Egger M, Davey Smith G, Altman DG (editors). Systematic Reviews in Health Care: Meta-analysis in Context (2nd edition). London (UK): BMJ Publication Group, 2001.

Engels 2000 
Engels EA, Schmid CH, Terrin N, Olkin I, Lau J. Heterogeneity and statistical significance in meta-analysis: an empirical study of 125 meta-analyses. Statistics in Medicine 2000; 19: 1707-1728.

GRADE Working Group 2004 
GRADE Working Group. Grading quality of evidence and strength of recommendations. BMJ 2004; 328: 1490-1494.

Lewis 2001 
Lewis S, Clarke M. Forest plots: trying to see the wood and the trees. BMJ 2001; 322: 1479-1480.