International Conference on Environmental Future Jyvaskyla, Finland, & Polunin, N. (1972). The environmental future: Proceedings of the first International Conference on Environmental Future, held in Finland from 27 June to 3 July 1971. Macmillan.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)International Conference on Environmental Future Jyvaskyla, Finland, و Nicholas Polunin. The Environmental Future: Proceedings of the First International Conference on Environmental Future, Held in Finland from 27 June to 3 July 1971. London: Macmillan, 1972.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)International Conference on Environmental Future Jyvaskyla, Finland, و Nicholas Polunin. The Environmental Future: Proceedings of the First International Conference on Environmental Future, Held in Finland from 27 June to 3 July 1971. Macmillan, 1972.