Citazione Stile APA (7a Edizione)

Helpman, E. (1997). R%D and productivity: The international connection. National Bureau of Economic Research.

Citazione stile Chigago Style (17a edizione)

Helpman, Elhanan. R%D and Productivity: The International Connection. Cambridge: National Bureau of Economic Research, 1997.

Citatione MLA (9a ed.)

Helpman, Elhanan. R%D and Productivity: The International Connection. National Bureau of Economic Research, 1997.