What brought the end of the Song Dynasty ?

What were some of the great finds that portuguese sailors discovered after prince henry established his navigational school in 1415? the gold coast and the cape verde islands gold and silver ore china the cape of good hope

How long does each side take in a supreme court case to make its oral argument

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.