
Hey, Professor Proton.
The Big Bang Theory Season 11, Episode 15

Nice to meet you, Professor Proton.
The Big Bang Theory Season 6, Episode 22

Here he comes, Professor Proton
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

SHELDON:
Nice to meet you, Professor Proton.
The Big Bang Theory Season 6, Episode 22