00400nam a2200121Ia 4500082001800000100004300018245007400061260003100135300002000166490005200186500000500238700003500243  a516bAb141.TG  aAbolson, Harold and Disessa, Andrea A.  aTurtle geometry; the computer as a medium for exploring mathematicsb  aCambridgebMIT Pressc1981  axx, 477p. Index  aThe MIT Press series in artificial intelligence  a  aDisessa, Andrea A. ; jt. auth.