00309nam a2200121Ia 4500008004100000082001500041100001700056245003500073260004300108300001200151942000700163999001700170190709s9999    xx            000 0 und d  a136.7 P571  aPiaget, Jean 0aChild's conception of geometry  aLondonbRoutledge and Kegan Paulc1960  avii,411  cBK  c39773d39773