00326nam a2200121Ia 45000030006000000080041000060400015000471000016000622450088000782600009001665460012001750050017001870STCL150530s9999    xx            000 0 und d  aSTCLcSTCL  aKeene, G.B.  aAbstract sets and finite ordinals an introduction to the study of set theory vol 23  c1961  aEnglish20220125165921.0