00333nam a2200121 a 450000500170000000800410001705000260005810000150008424500470009926000360014630000080018244000210019020140412111245.0070806s19uu    xx            00    eng d  aTR(GS 507bDi611 1989  aRobert Guy  aDiscover Science K :bT. Ed /cRobert Guy.  aU.S.A :bScott Foresman,c1989.  a134  aDiscover Science