Citazione Stile APA (7a Edizione)

Knorr, K. E., & Verba, S. (1961). The international system: Theoretical essays. Princeton University.

Citazione stile Chigago Style (17a edizione)

Knorr, Klaus E., e Sidney Verba. The International System: Theoretical Essays. Princeton: Princeton University, 1961.

Citatione MLA (9a ed.)

Knorr, Klaus E., e Sidney Verba. The International System: Theoretical Essays. Princeton University, 1961.