Boruvka, O. <br/><br/>
Foundations of the theory of groupoids and groups / 
O. Boruvka ; translated from the German by Milada Borukova 
 - New York :  Wiley & Sons,  1976 
 - 215 p. ;  24 cm. 
<br/><br/> Translation of Grundlagen der Gruppoid- und Gruppentheorie  'A Halsted Press book.'  Includes index 
<br/><br/>p. 203-209 
<br/><br/><br/>engger 
<br/><br/><label>ISBN: </label>0470089652 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Group theory<br/>Groupoids