Shaw, Peter & De Vet,Therese <br/><br/>
Using blackboard drawing No.5 

 - George Allen & Unwin, London  1980 
 - 128,pp 
<br/><br/><label>ISBN: </label>0 - 04 - 371075 -1 
<br/><br/><label>Dewey Class. No.: </label>428.24078 Sha/Dev