Learning by Expanding/ 
Yrjo Engestrom. 
 - Helsinki:  Orienta-Konsultit Oy,  c1987. 
 - ill.;v,368p.  21x14cm. 
<br/><br/><label>ISBN: </label>9519593322 
<br/><br/><label>Dewey Class. No.: </label>371.39ENG