
and where Leonard got his PhD,
so it may have gone downhill.
The Big Bang Theory Season 10, Episode 24

I have a PhD in astrophysics.
The Big Bang Theory Season 10, Episode 18

and where Leonard got his PhD,
so it may have gone downhill.
The Big Bang Theory Season 10, Episode 23

"Why Sheldon Cooper, PhD...
The Big Bang Theory Season 3, Episode 15

I must say, Amy, I was very impressed
to see that Bernadette got her PhD.
The Big Bang Theory Season 4, Episode 24