In 3 words or less, how would you rephrase "how did you hear about us?"?

I work for a law firm. I'm trying to come up with a database for our non- and existent customers. I need a column heading for one of our preliminary questionnaires which asks, "How did you hear about our firm?"





Thanks

In 3 words or less, how would you rephrase "how did you hear about us?"?
Know how
Reply:How about 'Refered by:"?
Reply:You could say





You know of us how?


You know us?


I know you _________________ (fill in blank)


I found out __________________ (fill in blank)





Thats all I got, but good luck and all!
Reply:Wurrdya findus?
Reply:If it's just for a column header, how about:


referred by
Reply:Referred by_______________


Recommended by________________
Reply:Hear of firm, learn of firm, learn of us, how find us, how learn us
Reply:heard from where??? i dont understand this question but i think that is what you mean by 3 words or less!
Reply:find us