00278nam a2200109 a 450000500170000000800410001704100080005810000210006624500340008726400390012130000080016020260717100932.0260717s1990    ii            000 0 eng d  aeng1 aVishishta, B. R.10aPteridophyta /cVishishta B.R 1aDelhi :bS.Chand & Company,c1990.  a512