When two or more sources are used to prove a historical event, the following procedure is applied to examine contradictory sources:
1. If sources all agree about an event, the historian can consider the event proved
2. Majority does not rule; critical textual analysis is necessary even if most sources relate events in one way
3. A source whose account can be confirmed by outside authorities in some parts can be trusted in its entirety
4. When two sources disagree, the historian will prefer the source with the most "authority"
5. Eyewitnesses are generally preferred, especially when dealing with facts known by most contemporaries
6. If two independently created sources agree on a matter, the reliability of each is enhanced
7. When two sources disagree and there is no other means of evaluation, historians choose the source that seems to accord best with common sense