United Nations Environment Programme & South Asia Co-operative Environment Programme. (2001). Sri Lanka: State of the environment, 2001. United Nations Environment Programme : Distributed by United Nations Environment Programme, Regional Resource Centre for Asia and the Pacific.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)United Nations Environment Programme و South Asia Co-operative Environment Programme. Sri Lanka: State of the Environment, 2001. Pathumthani, Thailand: United Nations Environment Programme : Distributed by United Nations Environment Programme, Regional Resource Centre for Asia and the Pacific, 2001.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)United Nations Environment Programme و South Asia Co-operative Environment Programme. Sri Lanka: State of the Environment, 2001. United Nations Environment Programme : Distributed by United Nations Environment Programme, Regional Resource Centre for Asia and the Pacific, 2001.