Answer:
Citing something that your friend says!
Step-by-step explanation:
Your friend aren't always reliable, reason being that they can lie to look smart. Also, a historian knows more than your "friend" If your friend doesn't have enough evidence to back up his/her/their reasonings, they are automatically incorrect. An encyclopedia isn't always reliable ether. I mean, there are THOUSANDS or different ones every day. How could you trust just one?
Hope this helped!