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2. 2) Polunin I., “Plants and Flowers of Singapore,” ed. by Time Editions, 1987 p. 42.
3. 3) Chin Y. W., “A Guide to the Ferns of Singapore,” ed. by Singapore Science Centre, 1983, pp. 43-44.
4. 4) Chin W. Y., Ferns and Fern Allies, “The Encyclopedia of Malaysia: Plants,” ed by Soepadmo E., Editions Didier Millet, 1998, p. 44.
5. 5) Vasuda S. M., Ind. Fern J., 16, 130-152 (1999).