Every scientist knows this pain. You present your findings at a conference, and some bearded guy in the third row demands "sources?" for basic knowledge. First, you stay calm. Then you politely mention your references. By the third interruption, you're sobbing "IT'S LITERALLY IN EVERY TEXTBOOK SINCE 1962!"
This is Hitchens' Razor in action: extraordinary claims require extraordinary evidence, but asking for citations on well-established facts is just academic torture. Next time someone asks you to prove water is wet, just hand them a glass and walk away.