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Maintenance of the biosphere : proceedings of the Third International Conference on Environmental Future (3rd ICEF)
Polunin, Nicholas, (1990)
THE ENVIRONMENTAL FUTURE : PROCEEDINGS OF THE FIRST INTERNAT. CONFERENCE ON ENVIRONMENTAL FUTURE, HELD IN FINLAND FROM 27 JUNE TO 3 JULY 1971 / ED. BY NICHOLAS POLUNIN
Polunin, Nicholas, (1972)
Surviving with the biosphere : proceedings of the Fourth International Conference on Environmental Future (4th ICEF), held in Budapest, Hungary, during 22-27 April 1990
Polunin, Nicholas, (1993)