World Tourism Organization. (1981). Organization and operation of the statistics service within the National Tourism Administration: Basic guidelines. The Organization.
Citazione stile Chigago Style (17a edizione)World Tourism Organization. Organization and Operation of the Statistics Service Within the National Tourism Administration: Basic Guidelines. Madrid: The Organization, 1981.
Citatione MLA (9a ed.)World Tourism Organization. Organization and Operation of the Statistics Service Within the National Tourism Administration: Basic Guidelines. The Organization, 1981.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.