00313nam a2200097Ia 4500008004100000040001100041245008400052260005300136300001700189300000900206251112s9999||||xx |||||||||||||| ||und||  aCNCLSA 0aProceedings of the National Academy Of Sciences of the United States of America  cSeptember 1, 1991bProc. Natl. Acad. Sci.aU.S.A  aP. 7459-8864  bV.46