Citations:
- http://www.history.com/topics/american-civil-war/civil-war-technology
- http://www.pbs.org/opb/historydetectives/feature/civil-war-innovations/
- http://www.scientificamerican.com/article/how-technology-shaped-the-civil-war-classics/
- http://www.pbs.org/wgbh/americanexperience/features/general-article/lincolns-camera/