00275nam a2200109Ia 4500008004100000082001500041100001700056245003200073250000800105260004100113300001100154190709s9999    xx            000 0 und d  a136.7 P71C  aPiaget, Jean 0aChilds conception of number  a3rd  aLondonbRoutledge & Kegan Paulc1964  aix,248