How did the allies directly begin their counter-attack on germany

Why is it useful for historians to base certain studies on the analysis of historical periods

Which of the following wrote detailed accounts about early native american? a) spanish b) french c) americans d) mexicansi need this !

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.