Organisation for Economic Co-operation and Development & Seminar on Environmental Benefits from Agriculture. (1997). Environmental benefits from agriculture: Issues and policies : the Helsinki Seminar. Organisation for Economic Co-operation and Development ; OECD Washington Center [distributor].
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Organisation for Economic Co-operation and Development و Seminar on Environmental Benefits from Agriculture. Environmental Benefits from Agriculture: Issues and Policies : The Helsinki Seminar. Paris : Washington D. C.: Organisation for Economic Co-operation and Development ; OECD Washington Center [distributor], 1997.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Organisation for Economic Co-operation and Development و Seminar on Environmental Benefits from Agriculture. Environmental Benefits from Agriculture: Issues and Policies : The Helsinki Seminar. Organisation for Economic Co-operation and Development ; OECD Washington Center [distributor], 1997.