1. Arber A. 1950:The natural philosophy of plant form Cambridge Univ. Press Cambridge.
2. Asama K. 1960:Evolution of the leaf forms through the ages explained by the succesive retardation and neoteny. Sci Rep. Tohoku Univ. Sendai Japan 2nd Ser. (Geol.) Spec. 4 254–258.
3. Bedome R. H. 1970:The ferns of Southern India Being descriptions and plates of the ferns. Today and tomorrow Print and Publ. New Delhi‐5 (India).
4. Bierhorst D. W. 1971:Morphology of vascular plants Macmillan New York.
5. Bierhorst D. W. 1973).Non‐appendicular fronds in the Filicales.. In:A. C.Jermy J. A.CrabbeandB. A.Thomas(Eds.) The phylogeny and classification of the ferns. Bot. J. Linn. Soc.67 Suppl. 1 45–57.