000			00292nam a2200121Ia 4500
008			210212s9999||||xx |||||||||||||| ||und||
082			_a512.7 Ope.L1
100			_aOpen University
245		0	_aNumber system
260			_c1971 _bOpen University _aBletchley
300			_a51p.
942			_cSU
999			_c100779 _d100779