Zellmer, D. (1999). The spectator: A World War II bomber pilot's journal of the artist as warrior. Praeger.
Citazione stile Chigago Style (17a edizione)Zellmer, David. The Spectator: A World War II Bomber Pilot's Journal of the Artist as Warrior. Westport, Conn.: Praeger, 1999.
Citatione MLA (9a ed.)Zellmer, David. The Spectator: A World War II Bomber Pilot's Journal of the Artist as Warrior. Praeger, 1999.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.