RCA Globetrotters Radio 7ft+ Sign.

I found this sign in my garage after buying my house. It was displayed in a Buick Dealership that sold RCA Radios. I believe it is from the 1930's but not sure. I can find no information on it. It is about 7ft tall and 4ft wide. Any information available? Where would I look? I also found several large RCA radio pictures in the same garage. They are about 3ft square with RCA related subjects. Some are a large picture some are collages. I have them stored now. They also look like 1930's era. Never seen any others like them either.