If you come across a date or statement of fact that you have reason to believe is untrue, and isn't properly attributed through links or notes, you may add the following template next to the suspicious claim:
{{citation needed}}
Readers are encouraged to find sources to back up or disprove claims followed by the "citation needed" meassage.
This template should not be used when a claim is already properly and reliably attributed, or when a claim can be verified with relative ease.