00292nam a2200109Ia 4500008004100000040003800041100002200079245003600101250000800137260002600145300001100171211215s9999    xx            000 0 und d  cJayakar Knowledge Resource Centre  aAlexandroff, Paul 0aElementary concepts of topology  a1st  bDoveraNew Yorkc1961  a73p p.