APA
Evenett S. J., Keller W., . (1998). On theories explaining the success of the gravity equation. Cambridge, Mass: National Bureau of Economic Research.
Chicago
Evenett Simon J, Keller Wolfgang, . 1998. On theories explaining the success of the gravity equation. Cambridge, Mass: National Bureau of Economic Research.
Harvard
Evenett S. J., Keller W., . (1998). On theories explaining the success of the gravity equation. Cambridge, Mass: National Bureau of Economic Research.
MLA
Evenett Simon J, Keller Wolfgang, . On theories explaining the success of the gravity equation. Cambridge, Mass: National Bureau of Economic Research. 1998.