00303nam a2200121 a 450000500170000002000150001708200130003210000320004524500140007726000380009130000290012963000230015820251202164143.0  a0716709465  a577bFRE  aScientific American .Incd_  aBiosphere  aSan FranciscobW.H. Freemanc1970  aviii, 134 p.  25 cm.cHB  aBiosphere, Ecology