Skyscrapers Sources 

Judith Dupre. Skyscrapers: A History of the World’s Most Extraordinary Building. Black Dog & Leventhal. November 5, 2013. Pgs. 14 – 15.  

Neal Bascomb. Higher: A Historic Race to the Sky and the Making of a City. Broadway Books. October 21, 2003. Pgs. 91 – 98.