
If you ever need a REFERENCE
or anything, just let me know.
The Big Bang Theory Season 9, Episode 23

And for future REFERENCE,
it's this.
The Big Bang Theory Season 5, Episode 12

Yeah, for future REFERENCE,
that's a while.
The Big Bang Theory Season 7, Episode 15

That is a cleverly veiled REFERENCE
to Howard's lifelong obsession...
The Big Bang Theory Season 6, Episode 9

What REFERENCE?
The Big Bang Theory Season 8, Episode 19