Selection
To select references:
Think about including and excluding criteria e.g.:
The PRISMA flow diagram might help you with this selection process.
Software tools for screening references
abstrackr - Abstract screening for systematic reviews.
SR Toolbox - Web based catalogue for SR tools.
Retraction check
Check retractions, corrections and expressions of concern of included references e.g. via Retraction Watch Database. Some reference managers (for example EndNote, Zotero) have been integrated with the Retraction Watch database.