Ravishankar Kumar Singh, E. (2003). Ecotourism and sustainable development.
シカゴスタイル引用形Ravishankar Kumar Singh, Ed. Ecotourism and Sustainable Development. Abhijeet Publications, Delhi, 2003.
MLA引用形式Ravishankar Kumar Singh, Ed. Ecotourism and Sustainable Development. 2003.
警告: この引用は必ずしも正確ではありません.