Is there a way I can find out all/many of the advertising agencies in state of Ohio. i.e. in cities like Columbus, Cleveland, Dayton, Akron, Cincinnati etc.

I cannot trust craiglist or any other job-search website anymore. I'm frustrated at running into scams most of the time.

Also, searching on google has not provided me with many fruitfully appropriate results

So I was wondering if anyone is aware of any websites or magazines or any other source of information which lists the advertising agencies in the different cities of ohio.

Help will be very appreciated. Thank you.