00393nam a2200121Ia 4500008004100000022001400041040001100055100002700066245008400093260006700177300001800244300000900262251112s9999||||xx |||||||||||||| ||und||  a0027-8424  aCNCLSA  aNicholas R. Cozzarelli 0aProceedings of the National Academy Of Sciences of the United States of America  cOctober 24, 1995bThe National Academy of SciencesaWashington  aP. 9911-12760  bV.94