References
NASA (n.d.) ‘Astronaut Candidate Program’, NASA [Online]. Available at https://astronauts.nasa.gov/content/broch00.htm (Accessed 21 September 2018).
Oxford dictionaries (2018) English Oxford Living Dictionaries [Online]. Available at https://en.oxforddictionaries.com/ definition/ centrifuge [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] (Accessed 4 October 2018).