Economics

https://usa.usembassy.de/etexts/oecon/chap3.htm

http://www.nytimes.com/2012/05/27/books/review/land-of-promise-by-michael-lind.html

http://www.hartford-hwp.com/archives/45/index-a.html

http://www.wsws.org/en/articles/2017/10/24/pers-o24.html

https://en.wikipedia.org/wiki/Economic_history_of_the_United_States

https://en.wikipedia.org/wiki/Economic_history_of_the_world

https://en.wikipedia.org/wiki/Economic_history_of_World_War_I