Cita APA (7th ed.)
Knorr, K., & Verba, S. The international system: Theoretical essays. Greenwood.
Cita Chicago (17th ed.)
Knorr, Klaus, i Sydney Verba. The International System: Theoretical Essays. Westport, EUA: Greenwood.
Cita MLA (9th ed.)
Knorr, Klaus, i Sydney Verba. The International System: Theoretical Essays. Greenwood.
Atenció: Aquestes cites poden no estar 100% correctes.