Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
From: Moher D., Liberati A., Tetzlaff J., Altman D.G. and The PRISMA Group (2009) Preferred Reporting /tems for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med.6(7), e1000097, doi:10.1371/journal.pmed1000097
