George R. R. Martin (2012). “George R. R. Martin's A Game of Thrones 5-Book Boxed Set (Song of Ice and Fire Series): A Game of Thrones, A Clash of Kings, A Storm of Swords, A Feast for Crows, and and A Dance with Dragons”, p.790, Bantam
"The Engineered Century". Neil Armstrong's remarks at the National Engineers Week on behalf of the National Academy of Engineering at the National Press Club, www.nae.edu. February 22, 2000.