Wulf, L. d., & .Sokol, J. B. (2004). Customs modernization initiatives: Case studies. World Bank.
Chicago (17e ed.) BronvermeldingWulf, Luc de, en Jose B. .Sokol. Customs Modernization Initiatives: Case Studies. Washington, DC: World Bank, 2004.
MLA (9e ed.) BronvermeldingWulf, Luc de, en Jose B. .Sokol. Customs Modernization Initiatives: Case Studies. World Bank, 2004.