
...caused by relative motion between
the SOURCE of the wave and the observer.
The Big Bang Theory Season 1, Episode 6

I know that money can
be a SOURCE of friction
The Big Bang Theory Season 12, Episode 3

Old age is a wonderful SOURCE of ironies,
Game of Thrones Season 4, Episode 9

So to begin with, what are we saying
is the SOURCE of this money?
Breaking Bad Season 3, Episode 11

she might not have been
a reliable SOURCE of information?
Game of Thrones Season 7, Episode 7