Why was mass production the more important reason the 1920s economic boom was sustained?

Who was marshall mcluhan and what did he have to do with communication theory?

What was an important consequence of the neolithic revolution? ):

What is the main difference between primary and secondary sources? a. primary sources are historical documents, and secondary sources are modern-day documents. b. primary sources are derived from museums and archives, and secondary sources are created by history students and academics. c. primary sources are found in ancient places with a rich history, and secondary sources are found in historical journals and blogs. d. primary sources are created during a particular historical era, and secondary sources are created by studying primary sources.