00397nam a2200121Ia 450000500170000000800410001702000210005805000160007910000210009524500900011626000420020665000270024820251229184636.0251229s9999    xx            000 0 und d  aLession planning  aLB 1134 .D3  aDavis, Robert H. 0aLearning system designban approach to the improvement of instructioncRobert H Davis  aNew Yorkb McGraw-Hill Book Co.c1974  aLearning Psychology Of