Helppp me plzzz APUSH QUESTIONS CHAPTER 17 and 18

Why was the battle of stalingrad a turning point in the european war

How did the governor's order that only georgian officers could command georgia's troops demonstrate a problem in the south

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.