United Nations Environment Programme Industry and Environment. (1998). Ecolabels in the tourism industry. UNEP.
Цитирование в стиле Чикаго (17-е изд.)United Nations Environment Programme Industry and Environment. Ecolabels in the Tourism Industry. Paris, France: UNEP, 1998.
Цитирование MLA (9-е изд.)United Nations Environment Programme Industry and Environment. Ecolabels in the Tourism Industry. UNEP, 1998.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.