00306nam a2200133 a 450000500170000002000180001708200160003510000210005124500170007226000220008930000270011149000130013870000210015120251203091745.0  a9780199633494  a572.86bBAT  aBates, Andrew D.  aDNA topology  aOxfordbOUPc1993  axii, 114p.c24 cm.bPB  aIn focus  aMaxwell, Anthony