Talking about credible sources. (p708 - 710)

• evaluate sources to see if they are:   
• authoritative   (author credentials, reputable source)
• accurate  (are facts/evidence verifiable?, if source accounts for alternative viewpoints, are they fairly represented?)
• objective  (is it presenting facts, are sources for evidence given, is the source academic, if not, what is its purpose?)
• current / relevant   (is info updated or reflecting recent discussions/changes)
• comprehensive   (does it demonstrate sufficient knowledge of the field)