Thomas, R. Murray <br/><br/>
An Instructional model for studying cognitive development and readability of instructional materials :  guidelines for evaluation / 
R. Murray Thomas. 
 - Paris :  New York :  Rome :  UNESCO;  UNICEF;  WFP,  1980. 
 - 14 p.;  fot. 
 - Notes, Comments...; 40 .
<br/><br/><label>No. de Clasificación Universal Decimal: </label>37.012 (910) =20 THO No.40.