00324    a2200121   4500020001500000082001300015100001700028245004900045260005000094300002100144650001800165700001900183  a8121908590  a570bVER  aVerma, P. S.  aEnvironmental biologybprinciples of ecology  aNew DelhibS.Chand  & Company Ltdc1983g1989  aviii,591p.c21cm  aLife sciences  aAgarwal, V. K.