World Tourism Organization. (1981). Organization and operation of the statistics service within the National Tourism Administration: Basic guidelines. The Organization.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)World Tourism Organization. Organization and Operation of the Statistics Service Within the National Tourism Administration: Basic Guidelines. Madrid: The Organization, 1981.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)World Tourism Organization. Organization and Operation of the Statistics Service Within the National Tourism Administration: Basic Guidelines. The Organization, 1981.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.