Zellmer, D. (1999). The spectator: A World War II bomber pilot's journal of the artist as warrior. Praeger.
Chicago Style (17th ed.) ZitazioaZellmer, David. The Spectator: A World War II Bomber Pilot's Journal of the Artist as Warrior. Westport, Conn.: Praeger, 1999.
MLA (9th ed.) ZitazioaZellmer, David. The Spectator: A World War II Bomber Pilot's Journal of the Artist as Warrior. Praeger, 1999.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.