Which are secondary sources? Select three options.

documentary about the Great Depression
textbook chapter about economic markets
book of historical fiction written about Dust Bowl refugees
letter home written by someone during the Great Depression
signed federal law aiding people affected by the Great Depression

How did the russian revolution impact world war i? a) the russians required the allied powers to come to their aid and defeat the radical groups. b) the russians pulled out from the war, enabling the germans to focus on the western front. c) the russians created new technological advancements that were used by the allied powers to win. d) the russians created a new communist government that aligned with the central powers instead.