Roddenberry 1964, p. 8. Roddenberry, Gene (1964). Star Trek(PDF). Los Angeles: Desilu Studios. Archived from the original(PDF) on 2016-05-12. Retrieved 2015-05-05.
Green, Michelle Erica (February 12, 2016). "Retro Review: Flashback". TrekNation. Archived from the original on March 20, 2016. Retrieved September 3, 2016.
Roddenberry 1964, p. 8. Roddenberry, Gene (1964). Star Trek(PDF). Los Angeles: Desilu Studios. Archived from the original(PDF) on 2016-05-12. Retrieved 2015-05-05.
Green, Michelle Erica (February 12, 2016). "Retro Review: Flashback". TrekNation. Archived from the original on March 20, 2016. Retrieved September 3, 2016.