World Tourism Organization. (1983). Development of a system of statistical indicators for travel and tourism. The Organization.
Chicago-referens (17:e uppl.)World Tourism Organization. Development of a System of Statistical Indicators for Travel and Tourism. Madrid: The Organization, 1983.
MLA-referens (9:e uppl.)World Tourism Organization. Development of a System of Statistical Indicators for Travel and Tourism. The Organization, 1983.
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