Cita APA (7th ed.)
Silverberg, R. Those who Watch. Signet : New American Library.
Cita Chicago (17th ed.)
Silverberg, Robert. Those Who Watch. Nueva York, EUA: Signet : New American Library.
Cita MLA (9th ed.)
Silverberg, Robert. Those Who Watch. Signet : New American Library.
Atenció: Aquestes cites poden no estar 100% correctes.