Professor Proton said
I should call him Arthur.
The Big Bang Theory Season 6, Episode 22
Professor Proton,
it's an honor to meet you.
The Big Bang Theory Season 6, Episode 22
All right,
Professor Proton fans,
The Big Bang Theory Season 12, Episode 16
Hey, I got an email
from Professor Proton.
The Big Bang Theory Season 7, Episode 7
Nice to meet you, Professor Proton.
The Big Bang Theory Season 6, Episode 22