British Travel Educational Trust. (1978). A comparative study of the provision of tourist information services in Western Europe annd North America. British Travel Educational Trust.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)British Travel Educational Trust. A Comparative Study of the Provision of Tourist Information Services in Western Europe Annd North America. London: British Travel Educational Trust, 1978.
توثيق جمعية اللغة المعاصرة MLA (الإصدار التاسع)British Travel Educational Trust. A Comparative Study of the Provision of Tourist Information Services in Western Europe Annd North America. British Travel Educational Trust, 1978.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.