1. Ten Great Events in History (chapter V: Columbus and the New World);Johonnot,2006
2. The Medieval & Early Modern World: Age of voyages, 1350-1600;Wiesner,2005
3. History.com, see http://www.history.com/news/famous-expeditions-that-fell-off-the-map (accessed 15.5.2015).
4. The Big Jump - Lindbergh and the Great Atlantic Air Race;Bak,2011
5. The Atlantic, http://www.theatlantic.com/international/archive/2014/04/mortality-on-mount-everest/360927/ (accessed 25.5.2015).