000 00250cam a2200109ua 4500
082 _a507.
_bUNE/SO
245 0 0 _aSource Book for Scientific Teaching /
250 _a2 /
260 _aGeneva :
_bUNESCO ,
_c1963.
300 _a252 ; .
942 _cREF
999 _c262966
_d262966