00336nam a2200121 a 4500008004100000020001500041050001500056245002900071246002400100260005100124300003000175350000900205080109s1977    ||||||||||||||||| ||    u  a033506292X  aQA 9.7 Ope10aModelling by mathematics  aThe Open University  aMilton KeynesbThe Open University Pressc1977  aIn various pagings : ill.  a0.00