Why have mohair farmers earned a subsidy from the federal government for decades?

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.

What is a firm that specializes in buying and selling stocks for individual investors called?

How does the power of the supreme court act as a check on the other branches of government