Sealey,L.G.W. <br/><br/>
Using the invicta abacus in relation to calculation 

 - England :  Invicta plastics ltd, 
 - 15p.;  22cm 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Social Sciences
<br/><br/><label>Dewey Class. No.: </label>372.7  / SEA