Urhausen, J. (2008). Tourism in Europe: Does age matter? Statistics in focus: Industry, trade and services.
Chicago-referens (17:e uppl.)Urhausen, Julia. "Tourism in Europe: Does Age Matter?" Statistics in Focus: Industry, Trade and Services 2008.
MLA-referens (8:e uppl.)Urhausen, Julia. "Tourism in Europe: Does Age Matter?" Statistics in Focus: Industry, Trade and Services, 2008.
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