1.··Nancy Bouchard, “Matter of Gravity, Petzl Turns the Vertical Environment into Bold Opportunity,” SGB Media, August 1, 2008.
2.··A. G. Lafley and Roger L. Martin, Playing to Win: How Strategy Really Works (Boston: Harvard Business Review Press, 2013).
3.··“Cost-Benefit Analysis Used in Support of the Space Shuttle Program,” National Aeronautics and Space Administration, June 2, 1972, http://archive.gao.gov/f0302/096542.pdf.
4.··发展航天飞机的概念起源于美国空军从1957年持续至1963年的「动力翱翔」（Dyna-Soar）计划，尼尔．阿姆斯特朗（Neil Armstrong）原为这计划下的试飞员。此计划的概念是设计与建造一架一接获通知就能立即携带武器至世界任何地方、并且像飞机般着陆的太空飞机，其灵感来自1942年的纳粹「美洲轰炸机」（Amerika Bomber）计划，该计划研究从欧洲轰炸美洲的几种可能选择。
5.··135次任务，2次失败，失败率为1.5％。「挑战者号」（Challenge）航天飞机上用于密封接缝的O形环在低温下失效，导致两段固态燃料火箭推进器未能密封，燃烧的高温气体外溢。「哥伦比亚号」航天飞机的隔热系统损坏是因为固态燃料箱的一块外壳脱落，撞击并损坏了一片绝热瓦。
6.··Jean Edward Smith, Eisenhower: In War and Peace (New York: Random House, 2012), 278.
7.··Maurice Matloff and Edwin Marion Snell, Strategic Planning for Coalition Warfare, 1941–1942 [1943–1944] (Office of the Chief of Military History, Department of the Army, 1953), 3:219.
8.··“President Bush Visits with Troops in Afghanistan at Bagram Air Base,” White House press release, https://georgewbush-whitehouse.archives.gov/news/releases/2008/12/20081215-1.html.
9.··Craig Whitlock, “At War with the Truth,” Washington Post, December 9, 2019.
