00303nam a2200109Ia 4500008004100000022001400041040001100055245005200066260005300118300001300171300000900184251112s9999||||xx |||||||||||||| ||und||  a0028-0836  aCNCLSA 0aNaturebInternational Weekly Journal of Science  cJanuary 4, 1990bMacmillan Magazines LtdaLondon  aP. 1-782  bV.52