The Referrer value returns the referrer of the current page.

Note that referrer can be url encoded. This means that "space" can be converted into %20 and so on.

To be on the safe side it is advisable to only use one word in the phrase you are targeting, when possible.

E.g. Use "Volvo" instead of "Volvo cars" and you avoid the problem.

Further reading

Creating your first events